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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > Engine Cranks But Does Not Run
Engine Cranks But Does Not Run
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Engine Cranks But Does Not Run
Refer to Engine Controls Schematics .
Circuit Description
The diagnosis for an engine that cranks but does not run must have three elements present before proceeding with the diagnostic table. The following conditions must exist:
• The battery must be adequately charged.
• The engine cranking speed must be sufficient.
• There must be an adequate amount of fuel in the fuel tank.
Diagnostic Aids
If no trouble is found in the fuel pump circuit or the ignition system and the cause of an Engine Cranks But Will Not Run has not been found, check the following conditions:
• Perform the Fuel Injector Solenoid Coil Test . see below
• An after-market vehicle theft deterrent system could cause a start then stall or a no start condition.
• Fouled spark plugs
• An EGR valve stuck open
• Water or foreign material in the fuel system
• A grounded or intermittently grounded Ignition Control (IC) signal circuit
• Restricted exhaust system. Refer to Restricted Exhaust in Engine Exhaust
• Check the following ignition components:
o A grounded tach circuit
o Worn distributor cap
o Worn distributor rotor
o Check ignition wires by lightly spraying them with water in order to identify intermittent no starts
Check the following mechanical components:
• Cylinder valve timing
• Loose or broken timing chain
• Low compression
• Worn camshaft lobes
• Bent or burned intake or exhaust valves
The VCM has integrated circuits that are fault protected; therefore, if a circuit has failed, the integrated circuit may not be damaged. If that is the case, the system will keep the circuit open until the condition has been corrected.
Afterwards, reinstall the VCM and check the circuit. Replace the VCM only if the circuit is still inoperative.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic tables.
2. If the engine starts, the problem could be intermittent. Basic engine mechanical problems, the vehicle theft deterrent (VTD) system (if equipped), and poor connections could cause a no start condition.
3. This step will determine if the cause of the no start or start and stall is related to the VTD.
4. If the signal is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems.
5. If the engine coolant sensor is below -30°C (-22°F), the VCM provides fuel for this extremely cold temperature which will severely flood the engine.
6. Voltage at the spark plug is checked using theJ 26792 spark plug tester tool. No spark indicates a basic ignition problem.
7. This test will determine if there is fuel pressure at the fuel injection unit and holding steady.
8. Use theJ 34730-375 injector test lamp in order to test the injector circuits. A blinking lamp indicates that the VCM is controlling the injector.
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool | | |(OBD) System Check |
| |Capture Info to save the Freeze Frame and the Failure | | |See below |
| |Records for reference. The control module's data is deleted| | | |
| |once the Clear Info function is used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) | | | |
| |System Check? | | | |
|2 |Attempt to start the engine. |-- |Go to Symptoms |Go to Step 3 |
| |Does the engine start and continue to run? | | | |
|3 |Install a scan tool. |-- |Go to Diagnostic System |Go to Step 4 |
| |Monitor the VTD Fuel Disabled parameter. | |Check - Theft Deterrent | |
| |Crank the engine. | |in Theft Deterrent | |
| |Does the VTD Fuel Disabled parameter display active while | | | |
| |you crank the engine? | | | |
|4 |Monitor the TP sensor on the scan tool. |2.5 V |Go to DTC P0121 Throttle|Go to Step 5 |
| |With the throttle closed, is the TP sensor more than the | |Position (TP) Sensor | |
| |specified value? | |Performance | |
|5 |Monitor the ECT sensor on the scan tool. |-30°C (-22°F) |Go to DTC P0118 Engine |Go to Step 6 |
| |Is the ECT sensor below the specified value? | |Coolant Temperature | |
| | | |(ECT) Sensor Circuit | |
| | | |High Voltage | |
|6 |Check for spark at two spark plug wires using the J 26792 |-- |Go to Step 7 |Go to Enhanced |
| |spark tester. | | |Ignition System |
| |Is spark present at both spark plug wires? | | |Diagnosis |
|7 |Reconnect the spark plug wires. |379-413 kPa |Go to Step 8 |Go to Fuel System |
| |Turn OFF the ignition. |(55-60 psi) | |Diagnosis |
| |Connect the J 34730-1A fuel pressure gauge. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Is the fuel pressure within the specified range? | | | |
|8 |Disconnect the injector connector at the intake manifold. |-- |Go to Diagnostic Aids |Go to Fuel Injector |
| |Install the J 34730-375 injector test lamp into each | | |Circuit Diagnosis |
| |injector circuit one at a time. | | | |
| |Crank the engine with the injector test lamp in each | | | |
| |circuit. | | | |
| |Does the injector test lamp flash for each injector | | | |
| |circuit? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > Fuel Injector Solenoid Coil Test
Fuel Injector Solenoid Coil Test
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Fuel Injector Solenoid Coil Test
|[pic] |
| |
|Click to Enlarge |
Test Description
The numbers below refer to the step numbers on the diagnostic able.
2. This step is used to set up the injector coil test. Also read the instructions included with the tools used for this test.
3. Engine coolant temperature affects the tool's ability to detect a faulty injector. If the engine coolant temperature is not between 50°F and 95°F, allow the vehicle to warm or cool as necessary.
4. Due to a current surge, the first second of the voltage reading may be inaccurate; therefore, begin recording after the first second of the voltage reading. The voltage specification should be within range. The voltage reading may increase throughout the test as the injector windings warm up and the resistance changes. An erratic voltage reading (one that jumps up and down) would indicate an intermittent connection within the fuel injector.
|Step |Action |Value(s) |Yes |No |
|1 |Was the Powertrain On-Board Diagnostic (OBD) System Check |-- |Go to Step 2 |Go to Powertrain On |
| |performed? | | |Board Diagnostic (OBD) |
| | | | |System Check |
|2 |CAUTION |10°-35°C |Go to Step 4 |Go to Step 3 |
| | | | | |
| |Caution: The fuel pump will operate for 2 seconds after you have| | | |
| |turned off the ignition. Make sure that all the fuel pipes and | | | |
| |fittings are securely fastened in order to prevent personal | | | |
| |injury. | | | |
| | | | | |
| |Turn OFF the engine. | | | |
| |Relieve the fuel pressure. Refer to Fuel Pressure Relief | | | |
| |Procedure . | | | |
| |Connect the fuel injector tester J 39021 to B+. | | | |
| |Connect the injector switch box J 39021-210 . | | | |
| |Set the amperage supply selection to the 0.5 amp position. | | | |
| |Connect the leads from J 39200 digital volt meter (DVM to the | | | |
| |tenths scale (0.0). | | | |
| |Connect the scan tool. | | | |
| |Monitor the engine coolant temperature. | | | |
| |Is the engine coolant temperature within the specified value? | | | |
|3 |Allow the engine to warm or cool as necessary. |10°-35°C |Go to Step 4 |-- |
| |Is the engine coolant temperature within the specified value? | | | |
|4 |WARNING |5.44-7.53V |Go to Step 5 |Go to Fuel Injector |
| | | | |Balance Test with Tech |
| |Important: Perform the following test for each injector. | | |2 |
| | | | | |
| |Press the Push To Start Test button. | | | |
| |Monitor the DVM. | | | |
| |WARNING | | | |
| | | | | |
| |Important: Voltage may climb during the test. Watch for erratic | | | |
| |readings (voltage that jumps up and down). | | | |
| | | | | |
| |Do any of the injector voltage readings fall outside the | | | |
| |specified value? | | | |
|5 |Replace the fuel injector and poppet nozzle assembly that was |5.44-7.53V |Go to Step 6 |-- |
| |not within the specified value. Refer to Fuel Injector | | | |
| |Replacement . | | | |
| |Is the action complete? | | | |
|6 |Using the scan tool, select the DTC and the Clear Info. |-- |Go to Step 7 |Go to Step 2 |
| |Attempt to start the engine. | | | |
| |Does the engine start and continue to run? | | | |
|7 |Allow the engine to idle until reaching the normal operating |-- |Go to the |Go to Step 8 |
| |temperature. | |applicable DTC | |
| |Select the DTC and the Failed This Ign. | |table | |
| |Are any DTCs displayed? | | | |
|8 |Use the scan tool in order to display the Capture Information |-- |Go to the |System OK |
| |and the Review Capture Information function. | |applicable DTC | |
| |Are any DTCs displayed that have not been diagnosed? | |table | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > Powertrain On Board Diagnostic (OBD) System Check
Powertrain On Board Diagnostic (OBD) System Check
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Powertrain On Board Diagnostic (OBD) System Check
Circuit Description
The On-Board Diagnostic (OBD) System Check is an organized approach to identifying a problem created by a control module system malfunction. The OBD is the starting point for any driveability concern diagnosis. The system check directs the service technician to the next logical step in diagnosing the concern.
Perform this check only if there is a driveability complaint or if you have been sent to this system check from another section in the service information.
Understanding the table properly reduces the diagnostic time. Proper use of the OBD helps prevent the unnecessary replacement of good parts.
Diagnostic Aids
|WARNING |
|Important: Do not clear the DTCs unless directed by a diagnostic procedure. Clearing the DTCs will also clear valuable Freeze Frame|
|and Failure Records data. |
Inspect all related wiring and connections including the connections at the VCM. These may cause an intermittent malfunction.
Any base engine problem could alter the scan tool data. Examples of these are: distributor timing, valve timing, and intake gasket leaks.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
1. This step determines if the scan tool powers up when connected to the DLC.
2. The MIL should be ON when you turn ON the ignition.
4. Refer to Diagnostic Trouble Code (DTC) List for a list of valid DTCs.
5. Refer to Data Link Connector Schematics in Data Link Communications in order to determine all of the modules communicating on the Class 2 Serial Data circuit. If any of the modules are not present in the Diagnostic Circuit Check, then the modules never established communications. The scan tool will indicate a YES state for communicating modules and a NO state for modules that had established yet no longer communicate.
7. If the vehicle does not start or starts and stalls, the Passlock system could be the cause.
8. This test determines if the MIL can be controlled by the VCM.
9. Comparing the ACTUAL and TYPICAL scan tool data values will aid in determining whether an engine parameter is within limits (i.e., Advanced timing can substantially alter sensor values.)
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Data Link |
| | | | |Connector Diagnosis |
| |Important: Check for applicable service bulletins before | | | |
| |proceeding with this test. | | | |
| | | | | |
| |Perform this test only if there is a driveability | | | |
| |complaint or if you have been sent to this table from | | | |
| |another section in the service information. | | | |
| |WARNING | | | |
| | | | | |
| |Important: Do not turn the ignition OFF when performing | | | |
| |this diagnostic. Do not clear the DTCs unless instructed | | | |
| |by this diagnostic. | | | |
| | | | | |
| |Turn ON the ignition leaving the engine OFF | | | |
| |Does the scan tool power up? | | | |
|2 |Turn ON the ignition leaving the engine OFF. |-- |Go to Step 3 |Go to Malfunction |
| |Is the MIL ON? | | |Indicator Lamp Circuit |
| | | | |Check |
|3 |Attempt to establish communications with the VCM. |-- |Go to Step 4 |Go to Data Link |
| |Does the scan tool communicate with the VCM? | | |Connector Diagnosis |
|4 |Save the DTC Freeze Frame and the Failure Records if any |-- |Go to the applicable |Go to Step 5 |
| |of the following DTC status are set in the scan tool DTC | |DTC table | |
| |Information: | | | |
| |Last Test Failed | | | |
| |Test Failed This Ignition | | | |
| |MIL Request | | | |
| |History DTC | | | |
| |Did you find any DTCs? | | | |
|5 |Monitor the Serial Data Class 2 messages with the scan |-- |Go to Step 6 |Go to Data Link |
| |tool. | | |Connector Diagnosis |
| |Are all other modules communicating with the scan tool? | | | |
|6 |Attempt to start the engine. |-- |Go to Step 8 |Go to Step 7 |
| |Does the engine start and continue to run? | | | |
|7 |Check for any Passlock DTCs in Body or Chassis. |-- |Go to the applicable |Go to Engine Cranks but|
| |Did you find any DTCs? | |DTC table |Does Not Run |
|8 |Command the MIL OFF with the scan tool. |Go to Step 9 |Go to Malfunction | |
| |Does the MIL turn OFF? | |Indicator Lamp Circuit | |
| | | |Check | |
|9 |Compare the scan tool engine data with the TYPICAL scan |-- |Go to Symptoms |Go to Diagnostic Aids |
| |tool values. | | | |
| |Are the values within typical ranges? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Body > Theft Deterrent > Diagnostic System Check - Theft Deterrent
Diagnostic System Check - Theft Deterrent
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Diagnostic System Check - Theft Deterrent
|[pic] |
| |
|Click to Enlarge |
Circuit Description
The Passlock system is designed to prevent engine operation if the correct key is not used to start the vehicle. The ignition key turns the lock cylinder, cylinder rotation produces an analog voltage code in the Passlock sensor.
The Passlock module receives this voltage code and is compared to the last learned voltage code. If the codes match, the Passlock module sends a class 2 message to the VCM, enabling the fuel injectors.
Diagnostic Aids
You must perform the Diagnsotic System Check prior to diagnosing any symptom or any Diagnostic Trouble Code table. Diagnose the DTCs in the order specified in the Passlock System "Displaying Diagnostic Trouble Codes" List. Failure to do so may result in the following conditions:
• Extended diagnostic time
• Incorrect diagnosis
• Incorrect parts replacement
If a Passlock module, a passlock sensor, or the VCM have been replaced, perform the learn procedure before following the Diagnostic System Check.
|Step |Action |Value(s) |Yes |No |
|1 |Connect a scan tool to the data link connector. |-- |Go to Step 2 |Go to Step 6 |
| |Can the scan tool be powered up? | | | |
|2 |Turn the ignition switch to the LOCK position. |-- |Go to SECURITY Indicator|Go to Step 3 |
| |Is the SECURITY telltale on? | |Always On or Flashing | |
|3 |Set the parking brake. |-- |Go to Step 4 |Go to SECURITY Indicator|
| |Reconnect any connectors or components previously | | |Inoperative |
| |disconnected. | | | |
| |Turn the ignition switch to the RUN position. | | | |
| |Monitor the SECURITY telltale for 10 seconds. | | | |
| |Did the SECURITY telltale turn on? | | | |
|4 |Did the SECURITY telltale turn on and remain on for more |-- |Go to Step 7 |Go to Step 5 |
| |than 6 seconds? | | | |
|5 |Does the SECURITY telltale flash? |-- |Go to Step 7 |Go to Step 9 |
|6 |Refer to Data Link Communications System Check in Data |-- |Go to Step 1 |-- |
| |Link Communications. | | | |
| |Is the repair complete? | | | |
|7 |Using the scan tool, test for current and history |-- |Go to SECURITY Indicator|Go to Step 8 |
| |Passlock DTC(s). | |Always On or Flashing | |
| |Does the scan tool display "No Communication with | | | |
| |Vehicle..."? | | | |
|8 |Is there any current Passlock DTC or a history B2958 DTC |-- |Go to Diagnostic Trouble|Go to SECURITY Indicator|
| |present? | |Code (DTC) Displaying |Always On or Flashing |
|9 |Attempt to start the vehicle. |-- |Go to Step 10 |Go to Step 13 |
| |Does the engine crank fast enough to start the vehicle? | | | |
|10 |Using the scan tool, monitor the "passlock code" from the|-- |Go to Engine Cranks But |Go to Step 11 |
| |Passlock Data List. | |Does Not Start | |
| |Does the scan tool read "Passlock Code Open"? | | | |
|11 |Does the engine start and run? |-- |System OK |Go to Step 12 |
|12 |Refer to Powertrain On Board Diagnostic (OBD) System |-- |Go to Step 1 |-- |
| |Check in Engine Controls - 4.3L. | | | |
| |Is the repair complete? | | | |
|13 |Refer to Starting System Check in Engine Electrical. |-- |Go to Step 1 |-- |
| |Is the repair complete? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > DTC P0121 Throttle Position (TP) Sensor Performance
DTC P0121 Throttle Position (TP) Sensor Performance
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
DTC P0121 Throttle Position (TP) Sensor Performance
|[pic] |
| |
|Click to Enlarge |
Circuit Description
The throttle position (TP) sensor is a potentiometer. The control module supplies the TP sensor a reference voltage, a signal, and ground circuits. When the throttle is depressed, the TP sensor signal rises to near the reference voltage. When the throttle is released, the TP sensor signal decreases from the reference voltage. The control module monitors the TP sensor signal circuit voltage in order to determine the throttle blade angle, or opening.
This DTC determines if the TP sensor signal input to the VCM does not closely match what the predicted value for the TP sensor should be. The VCM calculates what the TP signal voltage should be based on engine RPM. If the TP sensor voltage and the predicted TP sensor values do not closely match, this DTC will be set.
Conditions for Running the DTC
• DTC P0122 not active
• No active IAC DTCs
• No active MAP sensor DTCs
• The engine is running
• BARO not in default
• The throttle position is steady
Stuck High Test
MAP is less than 50 kPa
Stuck Low Test
• Stuck high test has passed
• MAP is more than 65 kPa
• The IAC is between 10-340 counts
Conditions for Setting the DTC
Stuck High Test
The throttle position is more than the calculated throttle position for more than 5 seconds.
Stuck Low Test
The throttle position is less than the calculated throttle position for less than 5 seconds.
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
• The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The scan tool displays the throttle position in volts. It should display about 0.45 volts to 0.85 volts with the throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT).
The scan tool will read the throttle angle percentage. 0 percent at closed throttle, 100 percent at Wide Open Throttle (WOT). A MAP related DTC could set if the TP throttle angle is skewed or stuck at a value of less than 20 percent.
Check the condition of the connector and sensor terminals for moisture or corrosion, and clean or replace as necessary. If corrosion is found, check the condition of the connector seal and repair or replace as necessary. If DTC P0121 is intermittent, refer to Symptoms .
Excessive throttle cable or cruise control cable tension could result in this DTC.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. The TP sensor has an auto zeroing feature. If the voltage reading is within the range of about 0.2- 0.9 volts, the VCM uses that value as a closed throttle. If the reading is out of the auto zero range at the closed throttle, check for a binding throttle shaft or damaged linkage. If the throttle shaft and the linkage are okay, continue with the diagnosis.
3. The TP sensor throttle angle should range smoothly from 0-100 percent when the throttle is slowly depressed to the wide open throttle (WOT) position. If not, a skewed out of range TP sensor, low reference voltage or a poor connection could be possible causes.
6. With the TP sensor disconnected, the TP sensor signal voltage should go low if the VCM and the wiring are okay and a DTC P0122 may set.
16. Reference voltage less than the 4.5 volts could cause a poor TP performance condition. Be sure to check both 5 volt reference circuits for conditions that could cause low voltage on the TP sensor circuit.
19. The throttle shaft, throttle linkage or accelerator cable not closing due to sticking or binding could cause a TP sensor poor performance condition.
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic (OBD)|
| |Important: Before clearing the DTCs, use the scan tool Capture | | |System Check |
| |Info to save the Freeze Frame and Failure Records for reference. | | | |
| |The control module's data is deleted once the Clear Info function | | | |
| |is used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Install the scan tool. |2% |Go to Step 6 |Go to Step 3 |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Does the scan tool display the throttle angle more than the | | | |
| |specified value? | | | |
|3 |WARNING |0-100% |Go to Step 4 |Go to Step 10 |
| | | | | |
| |Important: The engine must remain OFF for this step: | | | |
| | | | | |
| |Depress the throttle slowly to wide open throttle (WOT) while | | | |
| |watching the throttle angle increase through the specified range. | | | |
| |Does the TP sensor range reach the maximum specified value? | | | |
|4 |Release the throttle. |2% |Go to Step 6 |Go to Step 5 |
| |Does the scan tool display the throttle angle more than the | | | |
| |specified value? | | | |
|5 |The DTC is intermittent. |-- |Go to the |Go to Diagnostic Aids |
| |Are any additional DTCs set? | |applicable DTC | |
| | | |table | |
|6 |Disconnect the TP sensor harness connector. |0 V |Go to Step 7 |Go to Step 9 |
| |Does the scan tool display the TP sensor at the specified value? | | | |
|7 |Turn OFF the ignition. |-- |Go to Step 8 |Go to Step 14 |
| |Probe the TP sensor ground circuit with a test lamp connected to | | | |
| |B+. | | | |
| |Is the test lamp ON? | | | |
|8 |Turn ON the ignition leaving the engine OFF. |5.2 V |Go to Step 15 |Go to Step 19 |
| |Probe the TP sensor 5 volt reference circuit at the TP sensor | | | |
| |harness connector with a J 39200 DMM connected to a ground. | | | |
| |Is the voltage more than the specified value? | | | |
|9 |Turn OFF the ignition. |0 V |Go to Step 13 |Go to Step 22 |
| |Disconnect the VCM C2 connector. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Probe the TP sensor signal circuit at the TP sensor harness | | | |
| |connector with a J 39200 DMM connected to a ground. | | | |
| |Is the voltage more than the specified value? | | | |
|10 |Turn OFF the ignition. |100% |Go to Step 17 |Go to Step 11 |
| |Disconnect the TP sensor harness connector. | | | |
| |Jumper the TP sensor 5 volt reference circuit to the TP sensor | | | |
| |signal circuit at the TP sensor harness connector. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Does the scan tool display the throttle angle at the specified | | | |
| |value? | | | |
|11 |Turn ON the ignition leaving the engine OFF. |5.2 V |Go to Step 12 |Go to Step 16 |
| |Probe the TP sensor 5 volt reference circuit with a J 39200 DMM | | | |
| |connected to a ground. | | | |
| |Is the voltage near the specified value? | | | |
|12 |Turn OFF the ignition. |0? |Go to Step 22 |Go to Step 18 |
| |Disconnect the VCM C2 connector. | | | |
| |Check the resistance in the TP sensor signal circuit between the | | | |
| |TP sensor harness connector and the VCM connector with a J 39200 | | | |
| |DMM. | | | |
| |Is the resistance at the specified value? | | | |
|13 |Repair the short to voltage on the TP sensor signal circuit. Refer|-- |Go to Step 24 |-- |
| |to Wiring Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|14 |Repair the open in the TP sensor ground circuit. Refer to Wiring |-- |Go to Step 24 |-- |
| |Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|15 |Repair the short to voltage in the 5 volt reference circuit. Refer|-- |Go to Step 24 |-- |
| |to Wiring Repairsin Wiring Systems. | | | |
| |Is the action complete? | | | |
|16 |Repair the low voltage condition on the 5 volt reference circuit. |-- |Go to Step 24 |-- |
| |Refer to Wiring Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|17 |Check for a poor connection at the TP sensor. |-- |Go to Step 18 |Go to Step 19 |
| |Did you find a problem? | | | |
|18 |Repair the circuit as necessary. Refer to Wiring Repairs or |-- |Go to Step 24 |-- |
| |Connector Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|19 |Check the throttle shaft, linkage, throttle and cruise cables for |-- |Go to Step 20 |Go to Step 21 |
| |the following conditions: | | | |
| |Binding | | | |
| |Sticking | | | |
| |Did you find a problem? | | | |
|20 |Repair the throttle shaft, linkage or cables as necessary. |-- |Go to Step 24 |-- |
| |Is the action complete? | | | |
|21 |Replace the TP sensor. Refer to Throttle Position Sensor |-- |Go to Step 24 |-- |
| |Replacement. | | | |
| |Is the action complete? | | | |
|22 |Check for a poor connection at the VCM. Repair as necessary. Refer|-- |Go to Step 24 |Go to Step 23 |
| |to Connector Repairs in Wiring Systems. | | | |
| |Did you find a problem? | | | |
|23 |Replace the VCM. |-- |Go to Step 24 |-- |
| |Program the new VCM. Refer to VCM Replacement/Programming. | | | |
| |Perform the Passlock Reprogramming Procedure. Refer to PASSLOCK | | | |
| |Reprogramming Seed and Key in Theft Deterrent. | | | |
| |Perform the CKP System Variation Learn Procedure. Refer to | | | |
| |Crankshaft Position System Variation Learn. | | | |
| |Is the action complete? | | | |
|24 |Using the scan tool, clear the DTCs. |-- |Go to Step 25 |Go to Step 2 |
| |Start the Engine. | | | |
| |Allow the engine to Idle until the engine reaches normal operating| | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number which was set. | | | |
| |Operate the vehicle, with the Conditions for Setting this DTC, | | | |
| |until the scan tool indicates the diagnostic Ran. | | | |
| |Does the scan tool indicate the diagnostic Passed? | | | |
|25 |Does the scan tool display any additional undiagnosed DTCs? |-- |Go to the |System OK |
| | | |applicable DTC | |
| | | |table | |
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[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
|[pic] |
| |
|Click to Enlarge |
Circuit Description
The engine coolant temperature (ECT) sensor is a thermistor. The control module supplies the ECT sensor with a reference voltage on the ECT signal circuit and a ground circuit. When the ECT sensor resistance is high, indicating a cold sensor, the ECT sensor signal voltage remains near the supplied voltage. The ECT sensor decreases the signal voltage as the ECT sensor resistance is low, indicating a warm sensor. The control module monitors the ECT sensor signal circuit voltage in order to calculate the engine temperature.
This DTC is designed to detect an ECT sensor signal voltage higher than the possible range of a normally operating ECT sensor.
Conditions for Running the DTC
The engine has been running for more than 5 seconds.
Conditions for Setting the DTC
The ECT sensor voltage is more than 4.9 volts for more than 20 seconds.
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
• The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
After starting the engine, the ECT sensor temperature should rise steadily to about 90°C (194°F), then stabilize when the thermostat opens. Check for an intermittent open or short to battery voltage in the ECT sensor signal circuit. This may be accomplished by moving the VCM harness at various locations while monitoring the ECT temperature and voltage on the scan tool. If the voltage varies, look for an open or short to voltage in the area of the harness that caused the variance.
Use the Temperature vs Resistance Value table in order to test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed (mis-scaled) sensor. A skewed sensor could result in poor driveability complaints. Refer to Temperature vs Resistance .
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. If the condition is present, the ECT sensor voltage measures more than 4.9 volts.
3. This test simulates the conditions for a DTC P0117. If the VCM recognizes the grounded circuit (low voltage) and displays a low voltage message, the VCM and the wiring are okay.
4. This test checks for an open or grounded ECT sensor signal circuit. Also being checked are the ECT sensor ground circuit and the VCM.
5. This test checks for a short to voltage on the ECT sensor signal circuit.
12. After repairing a short to voltage, it is necessary to recheck the operation of the ECT sensor.
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic (OBD)|
| |Important: Before clearing the DTCs, use the scan tool Capture | | |System Check |
| |Info to save the Freeze Frame and Failure Records for reference. | | | |
| |The control module's data is deleted once the Clear Info function | | | |
| |is used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Install the scan tool. |4.9 V |Go to Step 3 |Go to Step 6 |
| |Start the engine. | | | |
| |Monitor the ECT sensor voltage. | | | |
| |Does the scan tool display an ECT sensor voltage more than the | | | |
| |specified value? | | | |
|3 |Turn OFF the engine. |0.82 V |Go to Step 5 |Go to Step 4 |
| |Disconnect the ECT sensor harness connector. | | | |
| |Jumper the ECT sensor harness terminals together. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Does the scan tool display an ECT sensor voltage less than the | | | |
| |specified value? | | | |
|4 |Jumper the ECT sensor signal circuit to a ground. |0.82 V |Go to Step 8 |Go to Step 9 |
| |Does the scan tool display an ECT sensor voltage less than the | | | |
| |specified value? | | | |
|5 |Disconnect the jumper. |5.20 V |Go to Step 10 |Go to Step 7 |
| |Check the voltage between the ECT sensor signal circuit and a | | | |
| |ground using a J 39200 DMM. | | | |
| |Is the voltage more than the specified value? | | | |
|6 |The DTC is intermittent. |-- |Go to the |Go to Diagnostic Aids |
| |Are any additional DTCs stored? | |applicable DTC | |
| | | |table | |
|7 |Check the ECT sensor harness connector and the VCM connector for a|-- |Go to Step 11 |Go to Step 13 |
| |proper connection. | | | |
| |Did you find a problem? | | | |
|8 |Check the ECT sensor ground circuit for an open or poor connection|-- |Go to Step 11 |Go to Step 14 |
| |between the ECT sensor and the VCM. | | | |
| |Did you find a problem? | | | |
|9 |Check the ECT sensor signal circuit for an open or poor connection|-- |Go to Step 11 |Go to Step 14 |
| |between the ECT sensor and the VCM. | | | |
| |Did you find a problem? | | | |
|10 |Repair the short to voltage in the ECT sensor signal circuit. |-- |Go to Step 12 |-- |
| |Refer to Wiring Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|11 |Repair the circuit as necessary. Refer to Wiring Repairs or |-- |Go to Step 15 |-- |
| |Connector Repairs in Wiring Systems. | | | |
| |Is the action complete? | | | |
|12 |Reconnect the ECT sensor harness. |4.9 V |Go to Step 15 |Go to Step 13 |
| |Start the engine. | | | |
| |Monitor the ECT sensor voltage. | | | |
| |Does the scan tool display an ECT sensor voltage less than the | | | |
| |specified value? | | | |
|13 |Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor|-- |Go to Step 15 |-- |
| |Replacement . | | | |
| |Is the action complete? | | | |
|14 |Replace the VCM. |-- |Go to Step 15 |-- |
| |Program the new VCM. Refer to VCM Replacement/Programming . | | | |
| |Perform the Passlock Reprogramming Procedure. Refer to PASSLOCK | | | |
| |Reprogramming Seed and Key in Theft Deterrent. | | | |
| |Perform the CKP System Variation Learn Procedure. Refer to | | | |
| |Crankshaft Position System Variation Learn . | | | |
| |Is the action complete? | | | |
|15 |Using the scan tool, clear the DTCs. |-- |Go to Step 16 |Go to Step 2 |
| |Start the Engine. | | | |
| |Allow the engine to Idle until the engine reaches normal operating| | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number which was set. | | | |
| |Operate the vehicle, with the Conditions for Setting this DTC, | | | |
| |until the scan tool indicates the diagnostic Ran. | | | |
| |Does the scan tool indicate the diagnostic Passed? | | | |
|16 |Does the scan tool display any additional undiagnosed DTCs? |-- |Go to the |System OK |
| | | |applicable DTC | |
| | | |table | |
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[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > Fuel System Diagnosis
Fuel System Diagnosis
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Fuel System Diagnosis
|[pic] |
| |
|Click to Enlarge |
Circuit Description
When you turn ON the ignition switch, the Vehicle Control Module (VCM) turns ON the in-tank fuel pump. The pump remains ON as long as the engine is cranking or running and the VCM is receiving reference pulses. If there are no reference pulses, the VCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops. The VCM will also turn ON the fuel pump for 2 seconds when the ignition is turned to the OFF position.
An electric fuel pump pumps the fuel through an in-line filter to the Central SFI unit. The pump is attached to the fuel level meter assembly inside of the fuel tank. The pump is designed to provide fuel pressure above what is needed by the fuel injectors. The pressure regulator keeps the fuel available to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank by the fuel return pipe.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Wrap a shop towel around the fuel pressure connection to absorb any small amount of fuel leakage that may occur when installing the fuel pressure gauge. Turn ON the ignition leaving the engine OFF, the fuel pressure should be 415-455 kPa (60-66 psi) when the pump is running. This pressure is controlled by a spring pressure within the regulator assembly.
4. The fuel pressure that continues to fall is caused by one of the following items:
o The in-tank modular fuel sender is not holding pressure.
o The fuel pressure regulator valve is leaking.
o A Central SFI injector is leaking.
o Fuel line is leaking.
15. If the fuel pressure is less than 379 kPa (55 psi) at idle, it falls into the following 3 areas:
o The pressure is regulated but less than 379 kPa (55 psi).The amount of fuel reaching the injector is sufficient, but the pressure is too low. The system will run lean, hard starting cold, no start, overall poor performance, and may set a DTC. Refer to Engine Cranks but Does Not Run .
o A restricted flow causing pressure drop -- Normally, a vehicle with a fuel pressure of less than 300 kPa (44 psi) at idle is inoperable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as the pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter.
o A leaking or contaminated pressure regulator valve or seat interface may not allow the regulated pressure to be achieved.
21.
|NOTE |
|Notice: DO NOT allow the fuel pressure to exceed 517 kPa (75 psi). Excessive pressure may damage the fuel |
|system. |
22. Restricting the fuel return line allows the fuel pressure to build above regulated pressure. With the fuel pump commanded ON, the fuel pressure should rise above 455 kPa (66 psi), as the valve in the return line is partially closed.
26. When the engine is idling, the manifold pressure is low (high vacuum) and is applied to the fuel pressure regulator diaphragm. This will offset the spring and result in a lower fuel pressure. This idle pressure will vary somewhat depending on the barometric pressure; however, the pressure at idle should be less indicating the pressure regulator control.
29. If the injector(s) is not grounded, physically remove suspect injector(s) and inspect for a fuel leak while system is pressurized. If the fuel injector(s) are not leaking and fuel pressure is not holding, the fuel pressure regulator should be inspected for a slow diaphragm leak.
|Step |Action |Value(s) |Yes |No |
|1 |Was the Powertrain On-Board Diagnostic (OBD) System Check |-- |Go to Step 2 |Go to Powertrain On |
| |performed? | | |Board Diagnostic |
| | | | |(OBD) System Check |
|2 |CAUTION |Central SFI - |Go to Step 3 |Go to step 8 |
| | |415-455 kPa | | |
| |Caution: The fuel pump will operate for 2 seconds after you have |(60-66 psi) | | |
| |turned off the ignition. Make sure that all the fuel pipes and | | | |
| |fittings are securely fastened in order to prevent personal | | | |
| |injury. | | | |
| | | | | |
| |Turn OFF the ignition for 10 seconds with the A/C OFF. | | | |
| |Relieve the fuel pressure. Refer to Fuel Pressure Relief . | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Wrap a shop towel around the fuel pressure connection in | | | |
| |order to reduce the risk of fire and personal injury. The towel | | | |
| |will absorb any fuel leakage that occurs during the connection of | | | |
| |the fuel pressure gage. Place the towel in an approved container | | | |
| |when the connection of the fuel pressure gage is complete. | | | |
| | | | | |
| |Install the fuel pressure gauge J 34730-1A or the equivalent. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Bleed the air out of the fuel pressure gauge into an approved | | | |
| |gasoline container. | | | |
| |Using the scan tool, again command the fuel pump ON. | | | |
| |Monitor the fuel pressure with the fuel pump running. It should | | | |
| |measure within the specified value. | | | |
| |WARNING | | | |
| | | | | |
| |Important: The fuel pump may have to be commanded ON more than | | | |
| |once in order to obtain the maximum fuel pressure. | | | |
| | | | | |
| |Is the fuel pressure within the specified value? | | | |
|3 |Using the scan tool, command the fuel pump ON. After the pump |Central SFI - |Go to Step 5 |Go to Step 4 |
| |stops, does the fuel pressure hold steady within the specified |379-413 kPa | | |
| |value? |(55-60 psi) | | |
|4 |Relieve the fuel pressure. Refer to Fuel Pressure Relief . |Central SFI - |Go to Step 12 |Go to Step 6 |
| |CAUTION |379-413 kPa | | |
| | |(55-60 psi) | | |
| |Caution: Place a dry chemical (Class B) fire extinguisher nearby | | | |
| |before performing any on-vehicle service procedures. Failure to | | | |
| |follow these precautions may result in personal injury. | | | |
| | | | | |
| | | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Provide proper ventilation when working with fuel in | | | |
| |enclosed areas where fuel vapors can collect. The lack of adequate| | | |
| |ventilation may result in personal injury. | | | |
| | | | | |
| |Disconnect the front plastic quick connect fitting from the fuel | | | |
| |filter. | | | |
| |Drain any remaining fuel from the fuel pipes into an approved | | | |
| |gasoline container. | | | |
| |Install the J 42873-1 in the place of the fuel filter. | | | |
| |Open the valve on the fuel pipe shut-off adapter. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Check for any leaks at the fuel shut-off adapter fittings. | | | |
| |Start the engine and let idle for 30 seconds. | | | |
| |Turn OFF the ignition. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Wait for the fuel pressure to build. | | | |
| |Close the valve in the fuel feed pipe shut-off. The pressure | | | |
| |should remain constant. | | | |
| |Does the fuel pressure remain constant within the specified value?| | | |
|5 |Is the fuel pressure suspected of dropping-off during |-- |Go to Step 27 |Go to Step 26 |
| |acceleration, cruise, or hard cornering? | | | |
|6 |Inspect the fuel feed line between the shut-off adapter and the |-- |Go to Step 25 |Go to Step 7 |
| |engine fuel pipes. | | | |
| |Was a problem found? | | | |
|7 |Open the valve in the fuel feed pipe shut-off adapter. |-- |Go to Step 22 |Go to Step 29 |
| |Relieve the fuel pressure. Refer to Fuel Pressure Relief . | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Place a dry chemical (Class B) fire extinguisher nearby | | | |
| |before performing any on-vehicle service procedures. Failure to | | | |
| |follow these precautions may result in personal injury. | | | |
| | | | | |
| | | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Provide proper ventilation when working with fuel in | | | |
| |enclosed areas where fuel vapors can collect. The lack of adequate| | | |
| |ventilation may result in personal injury. | | | |
| | | | | |
| |Disconnect the fuel return union fitting located near the fuel | | | |
| |filter. | | | |
| |Drain any remaining fuel from the fuel pipes into an approved | | | |
| |gasoline container. | | | |
| |Install the J 42873-2 in the place of the fuel return pipe union. | | | |
| |Open the valve in the fuel return pipe shut-off adapter. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Check for any leaks at the fuel shut-off adapter fittings. | | | |
| |Start the engine and let idle for 30 seconds. | | | |
| |Turn OFF the ignition. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Wait for the fuel pressure to build. | | | |
| |Close the valve in the shut-off adapter that is connected to the | | | |
| |fuel return pipe. | | | |
| |Does the fuel pressure remain constant? | | | |
|8 |Turn ON the ignition leaving the engine OFF. |-- |Go to Step 13 |Go to Step 9 |
| |Using the scan tool, command the fuel pump ON.The fuel pump should| | | |
| |operate for 2 seconds and then turn off. | | | |
| |Monitor the fuel pressure after fuel pump stops running. | | | |
| |Is the fuel pressure present? | | | |
|9 |Turn ON the ignition. |-- |Go to Step 10 |Go to Fuel Pump |
| |Using the scan tool, command the fuel pump ON. | | |Electrical Circuit |
| |Listen for the fuel pump running. | | |Diagnosis |
| |Does the fuel pump run? | | | |
|10 |Check for the following conditions: |-- |Go to Step 11 |Go to Step 12 |
| |No fuel in the fuel tank (do not rely on fuel gauge reading) | | | |
| |Plugged in-line fuel filter | | | |
| |Plugged or damaged fuel pump strainer | | | |
| |Restricted fuel line | | | |
| |Was a problem found? | | | |
|11 |Repair or replace as necessary. |-- |Go to Step 30 |-- |
| |Is the action complete? | | | |
|12 |Check for a leaking fuel feed pipe in between the shut-off adapter|-- |Go to Step 30 |-- |
| |and the modular fuel sender, if no leak is present, replace the | | | |
| |modular fuel sender. Refer to Fuel Sender Assembly Replacement . | | | |
| |Is the action complete? | | | |
|13 |Turn ON the ignition leaving the engine OFF. |Central SFI - |Go to Step 14 |Go to Step 15 |
| |Using the scan tool, command the fuel pump ON. |455 kPa (66 | | |
| |Monitor the fuel pressure while the pump is running. |psi) | | |
| |Is the fuel pressure above the specified value? | | | |
|14 |Relieve the fuel pressure. Refer to Fuel Pressure Relief . |Central SFI - |Go to Step 16 |Go to Step 17 |
| |CAUTION |415-455 kPa | | |
| | |(60-66 psi) | | |
| |Caution: Place a dry chemical (Class B) fire extinguisher nearby | | | |
| |before performing any on-vehicle service procedures. Failure to | | | |
| |follow these precautions may result in personal injury. | | | |
| | | | | |
| | | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Provide proper ventilation when working with fuel in | | | |
| |enclosed areas where fuel vapors can collect. The lack of adequate| | | |
| |ventilation may result in personal injury. | | | |
| | | | | |
| |Disconnect the engine compartment fuel return line | | | |
| |Attach a flex hose to the fuel return line. | | | |
| |Insert the other end into an approved gasoline container. | | | |
| |Using the scan tool, command the fuel pump ON while monitoring the| | | |
| |fuel pressure. | | | |
| |Is the fuel pressure within the specified value while the pump is | | | |
| |running? | | | |
|15 |Turn ON the ignition leaving the engine OFF. |Central SFI - |Go to Step 19 |Go to Step 30 |
| |Using the scan tool, command the fuel pump ON. |415 kPa (60 | | |
| |Monitor the fuel pressure while the pump is running. |psi) | | |
| |Is the fuel pressure below the specified value? | | | |
|16 |Locate and correct the restriction in the fuel return line. |-- |Go to Step 30 |Go to Step 17 |
| |Is the action complete? | | | |
|17 |Visually and physically inspect the engine fuel return outlet pipe|-- |Go to Step 18 |Go to Step 22 |
| |(where the fuel line was disconnected) for restriction. | | | |
| |Was a restriction found? | | | |
|18 |Replace the engine fuel pipes. Refer to Fuel Hose/Pipes |-- |Go to Step 30 |-- |
| |Replacement - Engine Compartment . | | | |
| |Is the action complete? | | | |
|19 |Perform the following items: |-- |Go to Step 20 |Go to Step 21 |
| |Check for a restricted fuel line. | | | |
| |Check for a restricted in-line fuel filter | | | |
| |Was a problem found? | | | |
|20 |Repair or replace as necessary the following items: |-- |Go to Step 30 |-- |
| |The restricted fuel line | | | |
| |The restricted fuel line filter | | | |
| |Is the action complete? | | | |
|21 |Relieve the fuel pressure. Refer to Fuel Pressure Relief . |Central SFI - |Go to Step 22 |Go to Step 23 |
| |CAUTION |455 kPa (66 | | |
| | |psi) | | |
| |Caution: Place a dry chemical (Class B) fire extinguisher nearby | | | |
| |before performing any on-vehicle service procedures. Failure to | | | |
| |follow these precautions may result in personal injury. | | | |
| | | | | |
| | | | | |
| |CAUTION | | | |
| | | | | |
| |Caution: Provide proper ventilation when working with fuel in | | | |
| |enclosed areas where fuel vapors can collect. The lack of adequate| | | |
| |ventilation may result in personal injury. | | | |
| | | | | |
| |Disconnect the fuel return pipe union located near the fuel | | | |
| |filter. | | | |
| |Drain any remaining fuel from the fuel pipes into an approved | | | |
| |gasoline container. | | | |
| |Install the J 42873-2 in the place of the fuel return pipe union. | | | |
| |Open the valve on the fuel return pipe shut-off adapter. | | | |
| |Using the scan tool, command the fuel pump ON. | | | |
| |Bleed the air out of the fuel pressure gauge into an approved | | | |
| |gasoline container. | | | |
| |Using the scan tool, again command the fuel pump ON. | | | |
| |NOTE | | | |
| | | | | |
| |Notice: DO NOT allow the fuel pressure to exceed 517 kPa (75 psi).| | | |
| |Excessive pressure may damage the fuel system. | | | |
| | | | | |
| |Slowly close the valve on the fuel return pipe shut-off adapter | | | |
| |while the pump is running. The pressure should rise above the | | | |
| |specified value. | | | |
| |Does the fuel pressure rise above the specified value? | | | |
|22 |Replace the fuel pressure regulator. Refer to Fuel Pressure |-- |Go to Step 30 |-- |
| |Regulator Replacement . | | | |
| |Is the action complete? | | | |
|23 |Perform the following items: |-- |Go to Step 24 |Go to Step 12 |
| |Check for low fuel pump voltage due to high resistance connections| | | |
| |Check for high fuel pump voltage due to internal pump binding | | | |
| |Check for a poor fuel pump ground | | | |
| |Check for a partially restricted fuel pump strainer | | | |
| |Check for an incorrect fuel pump | | | |
| |Check for a faulty fuel pump | | | |
| |Was a problem found? | | | |
|24 |Repair or replace as necessary. |-- |Go to Step 30 |-- |
| |Is the action complete? | | | |
|25 |Replace the fuel feed line. |-- |Go to Step 30 |-- |
| |Is the action complete? | | | |
|26 |Start the engine. |Central SFI - |Go to Driveability|Go to Step 27 |
| |Idle until the engine reaches the normal operating temperature. |415-455 kPa |Symptoms | |
| |Open the throttle quickly. |(60-66 psi) | | |
| |Monitor the fuel pressure. | | | |
| |The fuel pressure should approach the top of the specified range. | | | |
| |Does the fuel pressure rise quickly? | | | |
|27 |Visually and physically inspect the following items for a |-- |Go to Step 28 |Go to Step 12 |
| |restriction: | | | |
| |The in-line fuel filter for restriction. | | | |
| |The fuel feed pipe. | | | |
| |The fuel pump strainer must not be damaged or mispositioned. | | | |
| |The fuel pump flex pipe for leaks. | | | |
| |Verify the fuel pump is the correct fuel pump for this vehicle. | | | |
| |The fuel pump electrical wiring for high resistance. | | | |
| |Was a problem found in any of these areas? | | | |
|28 |Repair the problem as necessary. |-- |Go to Step 30 |-- |
| |Is the action complete? | | | |
|29 |Locate and replace any leaking or grounded injector(s). Refer to |-- |Go to Step 30 |Go to Fuel Injector |
| |Test Description for this step.For grounded injector diagnosis, | | |Balance Test with |
| |refer to Fuel Injector Circuit Diagnosis . | | |Tech 2 |
| |Is the action complete? | | | |
|30 |Use the scan tool in order to display the Capture Information and |-- |Go to the |System OK |
| |the Review Capture Information function. | |applicable DTC | |
| |Are there any DTCs displayed that have not been diagnosed? | |table | |
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[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.3L > Fuel Injector Circuit Diagnosis
Fuel Injector Circuit Diagnosis
|NOTE |
|Applicable vehicles: |
|Astro, Safari (VIN M/L) |
Fuel Injector Circuit Diagnosis
Refer to Fuel Injection Controls .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the ignition feed circuit to the injectors are OK.
6. This step determines if the injector control circuits are OK.
8. This step determines if there is an internal VCM short to ground for an injector control circuit.
Injector Circuit Diagnosis
|Step |Action |Value(s) |Yes |No |
|1 |Was the Powertrain On-Board Diagnostic (OBD) System Check |-- |Go to Step 2 |Go to Powertrain On |
| |performed? | | |Board Diagnostic (OBD) |
| | | | |System Check |
|2 |Disconnect the injector connector at the intake manifold. |-- |Go to Step 6 |Go to Step 3 |
| |Connect a test lamp to a ground. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Using the test lamp, probe the injector ignition feed circuits.| | | |
| |Is the test lamp on for all the injector feed circuits? | | | |
|3 |Is the test lamp on for only some of the injector feed |-- |Go to Step 5 |Go to Step 4 |
| |circuits? | | | |
|4 |Check the injector fuse. |-- |Go to Step 10 |Go to Step 11 |
| |Is the fuse open? | | | |
|5 |Check for an open on the effected injector feed circuits. Was a|-- |Go to Step 12 |-- |
| |problem found? | | | |
|6 |Install an injector test lamp J 34730-375 into each injector |-- |Go to Fuel |Go to Step 7 |
| |circuit one at a time. | |Injector Solenoid | |
| |Crank the engine. | |Coil Test | |
| |Does the injector test lamp flash for each injector? | | | |
|7 |Is the injector test lamp on steady for any injector circuit? |-- |Go to Step 8 |Go to Step 9 |
|8 |Install an injector test lamp in the effected circuit. |-- |Go to Step 16 |Go to Step 13 |
| |Turn OFF the ignition. | | | |
| |Disconnect the VCM Red connector. | | | |
| |Turn ON the ignition leaving the engine OFF. | | | |
| |Is the injector test lamp OFF? | | | |
|9 |Check for an open injector control circuit. |-- |Go to Step 12 |Go to Step 14 |
| |Was a problem found? | | | |
|10 |Check for a short to ground on the injector feed circuit. |-- |Go to Step 12 |-- |
| |Was a problem found? | | | |
|11 |Repair the open or short to ground on all of the injector feed |-- |Go to Step 17 |-- |
| |circuits. | | | |
| |Is the action complete? | | | |
|12 |Repair circuit as necessary. Refer to Wiring Repairs in Repair |-- |Go to Step 17 |-- |
| |Instructions. | | | |
| |Is the action complete? | | | |
|13 |Repair short to ground in the injector control circuit. Refer |-- |Go to Step 17 |-- |
| |to Wiring Repairs in Repair Instructions. | | | |
| |Is the action complete? | | | |
|14 |Check the terminal contact at the VCM. |-- |Go to Step 15 |Go to Step 16 |
| |Was a problem found? | | | |
|15 |Repair terminal contact as necessary. |-- |Go to Step 17 |-- |
| |Is action complete? | | | |
|16 |Replace the VCM. |-- |Go to Step 17 |-- |
| |Refer to VCM Replacement/Programming . | | | |
| |Perform the Passlock Reprogramming Procedure. Refer to PASSLOCK| | | |
| |Reprogramming Seed and Key in Theft Deterrent. | | | |
| |Perform the Crankshaft Variation Learn Procedure. Refer to | | | |
| |Crankshaft Position System Variation Learn . | | | |
| |Is the action complete? | | | |
|17 |WARNING |-- |Go to Step 18 |Go to Step 2 |
| | | | | |
| |Important:: Before starting the engine, it may be necessary to | | | |
| |check for fuel flooded cylinders or oil contamination (fuel). | | | |
| | | | | |
| |Using the scan tool, select the DTC and the Clear Info. | | | |
| |Attempt to start the engine. | | | |
| |Does the engine start and continue to run? | | | |
|18 |Allow the engine to idle until normal operating temperature is |-- |Go to the |Go to Step 19 |
| |reached. | |applicable DTC | |
| |Select the DTC and the Failed This Ign. | |table | |
| |Are any DTCs displayed that have not been diagnosed? | | | |
|19 |Use the scan tool in order to display the Capture Info and the |-- |Go to the |System OK |
| |Review Capture Info function. | |applicable DTC | |
| |Are there any DTCs displayed that have not been diagnosed? | |table | |
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