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|Trouble Code: P0171 (4.2L L6 VIN S Auto) |Print this code data[pic] |
|Fuel Trim System Lean | |
Number of Trips to Set Code: 1
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• CCM Details
Trouble Code Conditions:
DTCs P0013, P0014, P0017, P0030, P0036, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0206, P0220, P0222, P0223, P0230, P0300, P0326, P0327, P0332, P0411, P0412, P0418, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0502, P0503, P0506, P0507, P060D, P060E, P1101, P1133, P1134, P1380, P1381, P1516, P1681, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, P2176, P2430, P2431, P2432, P2433, P2440, P2444 are not set. The engine is in Closed Loop status. The engine coolant temperature (ECT) is between -7 and +120°C (+19.4 and +248°F). The intake air temperature is between -7 and +145°C (+19.4 and +293°F). The manifold absolute pressure (MAP) is between 15-100 kPa (2.2-14.5 psi). The mass air flow (MAF) is between 1-512 g/s. The vehicle speed is less than 132 km/h (82 mph). The engine speed is between 400-6,100 RPM. The barometric pressure is more than 72 kPa (10.4 psi). The fuel level is more than 10 percent. DTC P0171 runs continuously when the above conditions are met.
Possible Causes:
• Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• The system will go lean if an injector is not supplying enough fuel.
• A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel.
• Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to Intermittent Conditions .
|Trouble Code: P1516 (4.2L L6 VIN S Auto) |Print this code data[pic] |
|Throttle Actuator Control (TAC) Module Throttle Actuator | |
|Position Performance | |
Number of Trips to Set Code: 2
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• EVAP Details
• MIL Details
Trouble Code Conditions:
The ignition is ON. The ignition voltage is greater than 8 volts. The system is not in the battery save mode. The engine is running. DTC P0068 is not set. DTC P1516 runs continuously when the above conditions are met.
Possible Causes:
• Use the J 35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector.
• Poor connections at the PCM or at the component--Inspect the harness connectors for a poor terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections for the proper procedure.
• For intermittents, refer to Intermittent Conditions .
|PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.2L > DTC P0171 |Print[pic] |
DTC P0171
|NOTE |
|Applicable vehicles: |
|9-7x (VIN S/T) |
|Envoy, Rainier, TrailBlazer, Ascender (VIN S/T) |
DTC P0171
Circuit Description
The powertrain control module (PCM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop. During Open Loop, the PCM determines fuel delivery based on sensor signals, without heated oxygen sensor (HO2S) input. During Closed Loop the PCM adds HO2S inputs and level of purge to calculate short and long term fuel trim adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the fuel trim values will be less than 0 percent. The short term fuel trim values change rapidly in response to the HO2S voltage signals. The long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1 A block of cells contain information arranged in combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term fuel trim diagnostic is based on an average of cells currently being used. The PCM selects the cells based on the engine speed and load. If the PCM detects an excessively lean condition, DTC P0171 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0171 Fuel Trim System Lean
Conditions for Running the DTC
• DTCs P0013, P0014, P0017, P0030, P0036, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0206, P0220, P0222, P0223, P0230, P0300, P0326, P0327, P0332, P0411, P0412, P0418, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0502, P0503, P0506, P0507, P060D, P060E, P1101, P1133, P1134, P1380, P1381, P1516, P1681, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, P2176, P2430, P2431, P2432, P2433, P2440, P2444 are not set.
• The engine is in Closed Loop status.
• The engine coolant temperature (ECT) is between -7 and +120°C (+19.4 and +248°F).
• The intake air temperature is between -7 and +145°C (+19.4 and +293°F).
• The manifold absolute pressure (MAP) is between 15-100 kPa (2.2-14.5 psi).
• The mass air flow (MAF) is between 1-512 g/s.
• The vehicle speed is less than 132 km/h (82 mph).
• The engine speed is between 400-6,100 RPM.
• The barometric pressure is more than 72 kPa (10.4 psi).
• The fuel level is more than 10 percent.
• DTC P0171 runs continuously when the above conditions are met.
Conditions for Setting the DTC
• The long term fuel trim weighted average value is more than a calibrated value.
• The above condition is present for 2 seconds.
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
• Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• The system will go lean if an injector is not supplying enough fuel.
• A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel.
• Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to Intermittent Conditions .
Test Description
The number below refers to the step number on the diagnostic table.
8. If conditions were not corrected, a worn cam, worn intake or exhaust valves, or other engine mechanical failures may be at fault.
|Step |Action |Values |Yes |No |
|1 |Did you perform the Diagnostic System Check - Vehicle? |-- |Go to Step 2 |Go to Diagnostic |
| | | | |System Check - |
| | | | |Vehicle |
|2 |WARNING |-- |Go to Diagnostic |Go to Step 3 |
| | | |Trouble Code (DTC) | |
| |Important: Disregard any transmission symptoms, antilock brake | |List - Vehicle | |
| |system (ABS) indicators, and traction control system (TCS) | | | |
| |indicators until any fuel trim faults are repaired. A fuel trim | | | |
| |fault may cause default actions such as harsh shifts and | | | |
| |illumination of the ABS/TCS indicators. | | | |
| | | | | |
| |Are any DTCs other than P0171 also set? | | | |
|3 |Install a scan tool. |19% |Go to Step 4 |Go to Diagnostic |
| |Review the Freeze Frame/Failure Records and record the displayed | | |Aids |
| |data for this DTC. | | | |
| |Select the Fuel and Emission data list. | | | |
| |Start the engine. | | | |
| |Observe the Long Term FT parameter with a scan tool. | | | |
| |Is the Long Term FT parameter more than the specified value? | | | |
|4 |Operate the engine at idle. |200-800 mV |Go to Step 5 |Go to Step 6 |
| |Observe the heated oxygen sensor (HO2S) parameters with a scan tool.| | | |
| |Does the scan tool indicate that the HO2S parameters are within the | | | |
| |specified range and fluctuating? | | | |
|5 |Turn OFF the engine. |-- |Go to Step 9 |Go to Step 8 |
| |Visually and physically inspect the following items: | | | |
| |Splits, kinks, or improper connections at the vacuum hoses--Refer to| | | |
| |Emission Hose Routing Diagram . | | | |
| |Low fuel pressure--Refer to Fuel System Diagnosis . | | | |
| |Properly functioning fuel injectors--Refer to Fuel Injector | | | |
| |Diagnosis | | | |
| |Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis | | | |
| |. | | | |
| |Did you find and correct the condition? | | | |
|6 |Turn OFF the engine. |-- |Go to Step 7 |Go to DTC P0106 |
| |Turn ON the ignition, with the engine OFF. | | | |
| |Observe the manifold absolute pressure (MAP) sensor pressure | | | |
| |parameter with a scan tool. | | | |
| |The MAP sensor pressure should be within the range specified for | | | |
| |your altitude. Refer to Altitude Versus Barometric Pressure . | | | |
| |Do the MAP parameters indicate the correct barometric pressure? | | | |
|7 |Turn OFF the engine. |-- |Go to Step 9 |Go to Fuel System |
| |Inspect for the following conditions: | | |Diagnosis |
| |Proper HO2S installation | | | |
| |Electrical connectors and wires are secured and not contacting the | | | |
| |exhaust system | | | |
| |An open or a short to ground in the HO2S signal circuit | | | |
| |Did you find and correct the condition? | | | |
|8 |Operate the engine at idle. |-- |Go to Step 9 |Go to Symptoms - |
| |Inspect for the following conditions: | | |Engine Mechanical |
| |Secondary air injection (AIR) shut-off valve stuck open | | | |
| |Missing, loose, or leaking exhaust components | | | |
| |Vacuum leaks at the intake manifold, throttle body, and injector | | | |
| |O-rings | | | |
| |Leaks at the air intake ducts | | | |
| |Leaking crankcase ventilation system | | | |
| |Did you find and correct the condition? | | | |
|9 |WARNING |-- |Go to Step 2 |Go to Step 10 |
| | | | | |
| |Important: After repairs, use the scan tool Fuel Trim Reset function| | | |
| |in order to reset the Long Term Fuel Trim. | | | |
| | | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |WARNING | | | |
| | | | | |
| |Important: DO NOT clear codes with the engine running. The codes may| | | |
| |reset in the same ignition cycle. | | | |
| | | | | |
| |Clear the DTCs with a scan tool. | | | |
| |Turn OFF the ignition for 30 seconds. | | | |
| |Start the engine. | | | |
| |Operate the vehicle within the Conditions for Running the DTC. You | | | |
| |may also operate the vehicle within the conditions that you observed| | | |
| |from the Freeze Frame/Failure Records. | | | |
| |Did the DTC fail this ignition? | | | |
|10 |In order to ensure that the performance of the catalyst has not been|-- |Go to Step 11 |Go to DTC P0420 |
| |affected by the fault that set this DTC, operate the vehicle within | | | |
| |the Conditions for Running and setting DTC P0420 and verify that DTC| | | |
| |P0420 runs and passes. Refer to DTC P0420 . | | | |
| |Does the DTC run and pass? | | | |
|11 |Observe the Capture Info with a scan tool. |-- |Go to Diagnostic |System OK |
| |Are there any DTCs that have not been diagnosed? | |Trouble Code (DTC) | |
| | | |List - Vehicle | |
|PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 4.2L > DTC P1516 |Print[pic] |
DTC P1516
|NOTE |
|Applicable vehicles: |
|Envoy, Rainier, TrailBlazer, Ascender (VIN S/T) |
DTC P1516
Circuit Description
The commanded throttle position is compared to the actual throttle position based on accelerator pedal position (APP) and possibly other limiting factors. Both values should be within a calibrated range of each other. The powertrain control module (PCM) continuously monitors the commanded and actual throttle positions. This DTC sets if the values are greater than the calibrated range.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
Conditions for Running the DTC
• The ignition is ON.
• The ignition voltage is greater than 8 volts.
• The system is not in the battery save mode.
• The engine is running.
• DTC P0068 is not set.
• DTC P1516 runs continuously when the above conditions are met.
Conditions for Setting the DTC
• The difference between the predicted and the actual throttle position is more than a calibrated amount.
• The above condition is present for more than 0.5 second.
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
• The control module commands the TAC system to operate in the Reduced Engine Power mode.
• A message center or an indicator displays Reduced Engine Power.
• Under certain conditions the control module commands the engine OFF.
Conditions for Clearing the MIL/DTC
• The PCM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
• A History DTC clears after 40 consecutive warm-up cycles in which there are no failures reported of this diagnostic or any other emission related diagnostic.
• The scan tool clears the MIL/DTC.
Diagnostic Aids
The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 20 percent. This is referred to as the rest position. The throttle valve should not be completely closed nor should they be open any more than the specified amount. The throttle valve should move open and to the closed position without binding under the normal spring pressure. The throttle should NOT be free to move open or closed WITHOUT spring pressure. Replace the throttle body if any of these conditions are found.
|WARNING |
|Important: Operating the throttle blade with the Throttle Blade Control function of the scan tool may cause additional DTCs to set. |
|Do not attempt to diagnose DTCs set during this function. |
The scan tool has the ability to operate the throttle control system using Special Functions. Actuate the throttle valve using the throttle blade control function located in the Throttle Actuator Control (TAC) System menu. This function will operate the throttle valve through the entire range in order to determine if the throttle body and system operate correctly.
Check for the following conditions:
• Use the J 35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector.
• Poor connections at the PCM or at the component--Inspect the harness connectors for a poor terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections for the proper procedure.
• For intermittents, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
8. The throttle valve is spring loaded in a slightly open position and should move in either direction without binding. The throttle valve should always be under spring pressure.
11. When the ignition is turned ON, the PCM operates the throttle control motor to verify the integrity of the system prior to start-up. This can be seen by the momentary flash of the test lamp as the ignition is turned ON.
|Step |Action |Yes |No |
|Schematic Reference: Engine Controls Schematics |
|Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views |
|1 |Did you perform the Diagnostic System Check - Vehicle? |Go to Step 2 |Go to Diagnostic |
| | | |System Check - Vehicle|
|2 |Are DTCs P0120, P0220, P2120, P2125, P2135, P2138 also set? |Go to Diagnostic Trouble|Go to Step 3 |
| | |Code (DTC) List - | |
| | |Vehicle | |
|3 |WARNING |Go to Step 4 |Go to Step 5 |
| | | | |
| |Important: The throttle angle and pedal angle may not correspond during | | |
| |this procedure. | | |
| | | | |
| |Turn ON the ignition, with the engine OFF. | | |
| |Observe the Throttle Position (TP) Sensor 1 and 2 Angle parameters. | | |
| |Apply and release the accelerator pedal several times. | | |
| |Does the TP Sensor 1 and 2 Angle parameters increase as the pedal is | | |
| |applied and decrease as the pedal is released? | | |
|4 |Observe the Freeze Frame/Failure Records for this DTC. |Go to Step 5 |Go to Diagnostic Aids |
| |Start the engine. | | |
| |Operate the vehicle within the Conditions for Running the DTC. You may | | |
| |also operate the vehicle within the conditions that you observed from the| | |
| |Freeze Frame/Failure Records. | | |
| |Did the DTC fail this ignition? | | |
|5 |Turn ON the ignition, with the engine OFF. |Go to Step 6 |Go to Step 16 |
| |Probe both sides of the ETC fuse with a test lamp. | | |
| |Does the test lamp illuminate on both sides of the fuse? | | |
|6 |Turn OFF the ignition. |Go to Step 22 |Go to Step 7 |
| |Probe both sides of the ETC fuse with a test lamp. | | |
| |Does the test lamp illuminate on both sides of the fuse? | | |
|7 |Turn OFF the ignition. |Go to Step 8 |Go to Step 23 |
| |Disconnect the powertrain control module (PCM) connector containing the | | |
| |ETC ignition 1 voltage circuit. | | |
| |Connect a fused jumper from the powertrain relay coil control circuit at | | |
| |the PCM connector to a good ground. | | |
| |Probe the ETC ignition 1 voltage circuit with a test lamp connected to a | | |
| |good ground. | | |
| |Does the test lamp illuminate? | | |
|8 |Turn OFF the ignition. |Go to Step 24 |Go to Step 9 |
| |Inspect the throttle body for the following conditions. Refer to | | |
| |Diagnostic Aids: | | |
| |A throttle valve that is NOT in the rest position | | |
| |A throttle valve that is binding open or closed | | |
| |A throttle valve that is free to move open or closed WITHOUT spring | | |
| |pressure | | |
| |Did you find any of these conditions with the throttle body? | | |
|9 |WARNING |Go to Step 13 |Go to Step 10 |
| | | | |
| |Important: The test lamp may momentarily flash when testing these | | |
| |circuits. This is considered normal. | | |
| | | | |
| |Disconnect the throttle body harness connector. | | |
| |Turn ON the ignition, with the engine OFF. | | |
| |Probe the throttle actuator control (TAC) motor control 1 and 2 circuits | | |
| |with the test lamp connected to ground. | | |
| |Did the test lamp illuminate and remain illuminated on either circuit? | | |
|10 |WARNING |Go to Step 14 |Go to Step 11 |
| | | | |
| |Important: The test lamp may momentarily flash when testing these | | |
| |circuits. This is considered normal. | | |
| | | | |
| |Probe the TAC motor control 1 and 2 circuits with the test lamp connected| | |
| |to battery positive. | | |
| |Did the test lamp illuminate and remain illuminated on either circuit? | | |
|11 |Turn OFF the ignition. |Go to Step 12 |Go to Step 15 |
| |Connect the test lamp between the TAC motor control 1 and battery ground.| | |
| |Observe the test lamp as you turn ON the ignition. | | |
| |Does the test lamp flash ON and then turn OFF? | | |
|12 |Turn OFF the ignition. |Go to Step 18 |Go to Step 15 |
| |Connect a test lamp between the TAC motor control 2 circuit and battery | | |
| |ground. | | |
| |Observe the test lamp as you turn ON the ignition. | | |
| |Does the test lamp flash ON and then OFF? | | |
|13 |Turn OFF the ignition. |Go to Step 20 |Go to Step 19 |
| |Disconnect the PCM connector that contains the TAC motor control | | |
| |circuits. | | |
| |Turn ON the ignition, with the engine OFF. | | |
| |Probe the TAC motor control 1 and 2 circuits with the test lamp connected| | |
| |to ground. | | |
| |Does the test lamp illuminate? | | |
|14 |Turn OFF the ignition. |Go to Step 21 |Go to Step 19 |
| |Disconnect the PCM connector that contains the TAC motor control | | |
| |circuits. | | |
| |Probe the TAC motor control 1 and 2 circuits with the test lamp connected| | |
| |to battery positive. | | |
| |Does the test lamp illuminate? | | |
|15 |Turn OFF the ignition. |Go to Step 26 |Go to Step 19 |
| |Disconnect the PCM connector that contains the TAC motor controls | | |
| |circuits. | | |
| |Test TAC motor control 1 and 2 circuits for an open or high resistance. | | |
| |Repair the circuit as necessary. Refer to Wiring Repairs . | | |
| |Did you find and correct the condition? | | |
|16 |Test the ETC ignition 1 voltage circuit for a short to ground. Refer to |Go to Step 26 |Go to Step 17 |
| |Circuit Testing and Wiring Repairs . | | |
| |Did you find and correct the condition? | | |
|17 |Test the motor control 1 circuit for a short to ground. Refer to Circuit |Go to Step 26 |Go to Step 24 |
| |Testing and Wiring Repairs . | | |
| |Did you find and correct the condition? | | |
|18 |Test for a poor connection or terminal tension at the throttle body |Go to Step 26 |Go to Step 24 |
| |connector. Refer to Testing for Intermittent Conditions and Poor | | |
| |Connections and Connector Repairs . | | |
| |Did you find and correct the condition? | | |
|19 |Test for a poor connection or terminal tension at the PCM. Refer to |Go to Step 26 |Go to Step 25 |
| |Testing for Intermittent Conditions and Poor Connections and Connector | | |
| |Repairs . | | |
| |Did you find and correct the condition? | | |
|20 |Repair the short to voltage on the circuit where the test lamp remained |Go to Step 26 |-- |
| |illuminated. Refer to Wiring Repairs . | | |
| |Did you complete the repair? | | |
|21 |Repair the short to ground on the circuit where the test lamp remained |Go to Step 26 |-- |
| |illuminated. Refer to Wiring Repairs . | | |
| |Did you complete the repair? | | |
|22 |Repair the short to voltage on the ETC ignition 1 voltage circuit. Refer |Go to Step 26 |-- |
| |to Wiring Repairs . | | |
| |Did you complete the repair? | | |
|23 |Repair the open or high resistance in the ETC ignition 1 voltage circuit.|Go to Step 26 |-- |
| |Refer to Wiring Repairs . | | |
| |Did you complete the repair? | | |
|24 |Replace the throttle body assembly. Refer to Throttle Body Assembly |Go to Step 26 |-- |
| |Replacement . | | |
| |Did you complete the replacement? | | |
|25 |Replace the PCM. Refer to Control Module References for replacement, |Go to Step 26 |-- |
| |setup, and programming. | | |
| |Did you complete the replacement? | | |
|26 |Clear the DTCs with a scan tool. |Go to Step 2 |Go to Step 27 |
| |Turn OFF the ignition for 30 seconds. | | |
| |Start the engine. | | |
| |Operate the vehicle within the Conditions for Running the DTC. You may | | |
| |also operate the vehicle within the conditions that you observed from the| | |
| |Freeze Frame/Failure Records. | | |
| |Did the DTC fail this ignition? | | |
|27 |Observe the Capture Info with a scan tool. |Go to Diagnostic Trouble|System OK |
| |Are there any DTCs that have not been diagnosed? |Code (DTC) List - | |
| | |Vehicle | |
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