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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.4L > Electric Cooling Fan Diagnosis
Electric Cooling Fan Diagnosis
|NOTE |
|Applicable vehicles: |
|Alero, Grand Am (VIN N) |
Electric Cooling Fan Diagnosis
|Table 1: |Electric Cooling Fan Functional Check |
|Table 2: |Electric Cooling Fan Table #1 |
|Table 3: |Electric Cooling Fan Table #2 |
|Table 4: |Electric Cooling Fan Table #3 |
Refer to Engine Controls Schematic Cooling Fans .
Circuit Description
Power for the fan motors is supplied through the underhood junction block. Refer to Engine Control Components Underhood Junction Block . The cooling fan relays are energized when current flows from the Cool Fan #1 fuse and the Cool Fan #2 fuse in the underhood junction block through the relay coils to ground through the powertrain control module (PCM). The LH fan control circuit is grounded for low speed fans operation. The LH fan control circuit and the RH fan control circuits are both grounded for high speed fans operation.
During low speed fans operation the PCM supplies a ground path for the #1 fan control relay. This closes #1 fan control relay contacts, allowing current to flow from the underhood junction block through the relay contacts to the LH cooling fan motor. During low speed fans operation, the ground path for the LH cooling fan motor is through the mode control relay and the RH cooling fan motor. The result is a series circuit with both cooling fans running at low speed.
During high speed fans operation the PCM supplies a ground path for the #1 fan control relay and then the mode control and the #2 fan control relay. This closes all 3 cooling fan relays. During high speed fans operation, both the LH cooling fan motor and the RH cooling fan motor are supplied current from the underhood junction block and each cooling fan has its own ground path through the ground splice pack. Refer to Engine Control Components Ground Splice Pack .
Diagnostic Aids
If the owner complained of an overheating problem, determine if the complaint was due to an actual boil over, the warning indicator illuminated, or the engine coolant temperature gauge indicated overheating. The gauge accuracy can also be tested by comparing the ECT sensor reading using a scan tool and comparing its reading with the gauge reading. If the engine is actually overheating and the gauge indicated overheating, but the cooling fans are not turning on, the ECT sensor may have shifted out of calibration and should be replaced. If the engine is overheating and the cooling fans are ON, the cooling system is suspect and should be inspected.
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
|WARNING |
|Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when |
|diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion. |
• Loose terminal connection
o Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
o Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to numbers on the diagnostic table:
2. The PCM will enable the engine cooling fans when certain DTCs are set. Refer to applicable DTC table first before proceeding with this table.
3. Allow ECT to cool below 100°C (212°F) before proceeding with diagnosis.
Electric Cooling Fan Functional Check
|Step |Action |Values |Yes |No |
|1 |Did you perform the Powertrain On Board Diagnostic |-- |Go to Step 2 |Go to Powertrain On Board|
| |(OBD) System Check? | | |Diagnostic (OBD) System |
| | | | |Check |
|2 |Are any DTCs set? |-- |Go to applicable DTCs |Go to Step 3 |
|3 |Install a scan tool. |100°C |Go to Step 4 |Go to Electric Cooling |
| |Engine coolant temperature must be below the specified |(212°F) | |Fan Diagnosis Electric |
| |value for all the fan diagnoses. | | |Cooling Fan Table #1 |
| |Turn ON the ignition, with the engine and A/C OFF. | | | |
| |Are the cooling fans OFF? | | | |
|4 |With a scan tool, command Low Speed Fans ON. |-- |Go to Step 5 |Go to Electric Cooling |
| |Are both cooling fans ON? | | |Fan Diagnosis Electric |
| | | | |Cooling Fan Table #2 |
|5 |WARNING |-- |Go to Step 6 |Go to Electric Cooling |
| | | | |Fan Diagnosis Electric |
| |Important: Allow a 3-5 second delay before determining | | |Cooling Fan Table #3 |
| |if the fans have switched from low to high speed. | | | |
| | | | | |
| |With a scan tool, command high speed fans ON. | | | |
| |Do both cooling fans switch to high speed? | | | |
|6 |Exit outputs screen on the scan tool. |-- |Go to Step 8 |Go to Step 7 |
| |Idle the engine leaving the A/C OFF. | | | |
| |Are the cooling fans ON? | | | |
|7 |Turn ON the A/C. |-- |System OK |Go to Step 9 |
| |Are the cooling fans ON? | | | |
|8 |Does the scan tool display A/C request as YES? |-- |Go to Cooling Insufficient|Go to Step 10 |
| | | |- Air Conditioning (A/C) | |
| | | |System in Heating, | |
| | | |Ventilation and Air | |
| | | |Conditioning | |
|9 |Does the scan tool display A/C request as YES? |-- |Go to Powertrain Control |Go to Cooling |
| | | |Module Controlled Air |Insufficient - Air |
| | | |Conditioning (A/C) Circuit|Conditioning (A/C) System|
| | | |Diagnosis |in Heating, Ventilation |
| | | | |and Air Conditioning |
|10 |WARNING |-- |System OK |-- |
| | | | | |
| |Important: The replacement PCM must be programmed. | | | |
| | | | | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
Electric Cooling Fan Table #1
|Step |Action |Values |Yes |No |
|1 |Did you perform the Electric Cooling Fan Functional Check? |-- |Go to Step 2 |Go to Electric |
| | | | |Cooling Fan |
| | | | |Diagnosis |
| | | | |Functional Check |
|2 |Disconnect #1 fan control relay. |-- |Go to Step 8 |Go to Step 3 |
| |Are both fans OFF? | | | |
|3 |Disconnect mode control relay. |-- |Go to Step 4 |Go to Step 10 |
| |Are both fans OFF? | | | |
|4 |Disconnect the left fan. |-- |Go to Step 11 |Go to Step 5 |
| |Probe terminal B of the left fan connector using a test lamp that is | | | |
| |connected to ground. | | | |
| |Does the test lamp illuminate? | | | |
|5 |Probe terminal A of the left fan connector using a test lamp that is |-- |Go to Step 12 |Go to Step 6 |
| |connected to ground. | | | |
| |Does the test lamp illuminate? | | | |
|6 |Probe the right fan control circuit (473) at the mode control relay |-- |Go to Step 7 |Go to Step 13 |
| |connector location (86) using a test lamp that is connected to | | | |
| |battery positive voltage. | | | |
| |Does the test lamp illuminate? | | | |
|7 |Turn OFF the ignition. |-- |Go to Step 14 |Go to Step 16 |
| |Leave the test lamp installed. | | | |
| |Disconnect the PCM. | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |Is the test lamp still illuminated? | | | |
|8 |Probe the left fan control circuit (335) at the #1 fan control relay |-- |Go to Step 9 |Go to Step 13 |
| |connector location (85) using the test lamp that is connected to | | | |
| |battery positive voltage. | | | |
| |Does the test lamp illuminate? | | | |
|9 |Turn OFF the ignition. |-- |Go to Step 14 |Go to Step 16 |
| |Leave the test lamp installed. | | | |
| |Disconnect the PCM. | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |Is the test lamp still illuminated? | | | |
|10 |Inspect the following components for a short to voltage: |-- |Go to Electric |Go to Step 15 |
| |The right fan feed circuit (532)--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you find and correct the condition? | | | |
|11 |Inspect the following components for a short to voltage: |-- |Go to Electric |-- |
| |The left fan feed circuit (409)--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|12 |Inspect the following components for a short to voltage: |-- |Go to Electric |-- |
| |The #2 fan control relay switch feed circuit (532)--Refer to Wiring | |Cooling Fan | |
| |Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|13 |Replace the #1 fan control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|14 |Inspect the following components for a short to ground: |-- |Go to Electric |-- |
| |The right fan control circuit (473)--Refer to Wiring Repairs in | |Cooling Fan | |
| |Wiring Systems. | |Diagnosis | |
| |The left fan control circuit (335)--Refer to Wiring Repairs in Wiring| |Functional Check | |
| |Systems. | | | |
| |Underhood junction block--Refer to Engine Controls Component Views | | | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|15 |Replace the #2 fan control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|16 |WARNING |-- |Go to Electric |-- |
| | | |Cooling Fan | |
| |Important: The replacement PCM must be programmed. | |Diagnosis | |
| | | |Functional Check | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
Electric Cooling Fan Table #2
|Step |Action |Values |Yes |No |
|1 |Did you perform the Electric Cooling Fan Functional Check? |-- |Go to Step 2 |Go to Electric |
| | | | |Cooling Fan |
| | | | |Diagnosis |
| | | | |Functional Check |
|2 |Did either fan turn ON when the Low Speed Fans were commanded ON? |-- |Go to Step 3 |Go to Step 4 |
|3 |Disconnect the mode control relay. |-- |Go to Step 17 |Go to Step 20 |
| |Turn ON the ignition. | | | |
| |Did the left fan turn OFF? | | | |
|4 |Disconnect the #1 fan control relay. |-- |Go to Step 5 |Go to Step 12 |
| |Probe the left fan control circuit (335) at the #1 fan control relay | | | |
| |connector terminal (85) using a J 35616-200 test lamp that is | | | |
| |connected to battery positive voltage. | | | |
| |With a scan tool, command the Low Speed Fans ON. | | | |
| |Does the test lamp illuminate? | | | |
|5 |Probe both feed circuits at the #1 fan control relay connector |-- |Go to Step 6 |Go to Step 16 |
| |terminals, 30 and 86, using a test lamp that is connected to ground. | | | |
| |Does test lamp illuminate for both circuits? | | | |
|6 |WARNING |-- |Go to Step 22 |Go to Step 7 |
| | | | | |
| |Important: Leave jumper in place for remainder of this table. | | | |
| | | | | |
| |Connect a fused jumper wire between the switch feed circuit and the | | | |
| |left fan feed circuit (409) at the #1 fan control relay connector | | | |
| |terminals 30 and 87. | | | |
| |Do both fans turn ON? | | | |
|7 |Disconnect the left fan. |-- |Go to Step 8 |Go to Step 23 |
| |Probe the left fan harness connector terminal B with a test lamp that | | | |
| |is connected to ground. | | | |
| |Does the test lamp illuminate? | | | |
|8 |Connect a second fused jumper wire between the left fan harness |-- |Go to Step 15 |Go to Step 9 |
| |connector terminals. | | | |
| |Is the right fan ON? | | | |
|9 |Reconnect the left fan. |-- |Go to Step 10 |Go to Step 24 |
| |Disconnect the mode control relay. | | | |
| |Probe the switch feed circuit (504) at the mode control relay | | | |
| |connector terminal (30) using a test lamp that is connected to ground.| | | |
| |Does the test lamp illuminate? | | | |
|10 |Using a second jumper wire, jumper the switch feed circuit (504) and |-- |Go to Step 26 |Go to Step 11 |
| |the right fan feed circuit (532) together at the mode control relay | | | |
| |connector terminals 30 and 87A. | | | |
| |Do the fans come ON? | | | |
|11 |Reconnect mode control relay. |-- |Go to Step 15 |Go to Step 17 |
| |Disconnect the right fan. | | | |
| |Probe fan harness connector terminal B with a test lamp that is | | | |
| |connected to ground. | | | |
| |Did the test lamp illuminate? | | | |
|12 |Turn OFF the ignition. |-- |Go to Step 14 |Go to Step 25 |
| |Disconnect the PCM. | | | |
| |Probe the left fan control circuit at the PCM connector, with a fused | | | |
| |jumper wire that is connected to ground. | | | |
| |Does the test lamp illuminate? | | | |
|13 |Inspect the PCM connector for poor and intermittent connections. Refer|-- |Go to Electric |Go to Step 27 |
| |to Testing for Intermittent Conditions and Poor Connections and | |Cooling Fan | |
| |Connector Repairs in Wiring Systems. | |Diagnosis | |
| |Did you find and correct the condition? | |Functional Check | |
|14 |Inspect the following components for a short to battery positive |-- |Go to Electric |-- |
| |voltage: | |Cooling Fan | |
| |The left fan control circuit (335)--Refer to Wiring Repairs in Wiring | |Diagnosis | |
| |Systems. | |Functional Check | |
| |Underhood junction block--Refer to Engine Controls Component Views | | | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|15 |Inspect the following components for a open: |-- |Go to Electric |Go to Step 21 |
| |The fan motor ground circuit--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |The fan motor connections-- Refer to Testing for Intermittent | |Functional Check | |
| |Conditions and Poor Connections , and Connector Repairs in Wiring | | | |
| |Systems. | | | |
| |Underhood junction block--Refer to Engine Controls Component Views | | | |
| |Underhood Junction Block . | | | |
| |Ground splice pack--Refer to Engine Controls Component Views Ground | | | |
| |Splice Pack . | | | |
| |Repair as needed. | | | |
| |Did you find and correct the condition? | | | |
|16 |Inspect for an open or short to ground in the circuit that did not |-- |Go to Electric |-- |
| |illuminate the test lamp | |Cooling Fan | |
| |Replace the fuse if necessary. | |Diagnosis | |
| |If this does not correct the problem, replace the underhood junction | |Functional Check | |
| |block. Refer to Engine Controls Component Views Underhood Junction | | | |
| |Block . | | | |
| |Did you complete the repair? | | | |
|17 |Inspect the following components for an open or short to ground: |-- |Go to Electric |Go to Step 26 |
| |The right fan feed circuit (532)--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Replace Cool Fan #2 Fuse if necessary. Repair as needed. | | | |
| |Did you complete the repair? | | | |
|18 |Replace the fan which was not operating. Refer to Engine Cooling Fan |-- |Go to Electric |-- |
| |Replacement in Engine Cooling. | |Cooling Fan | |
| |Did you complete the replacement? | |Diagnosis | |
| | | |Functional Check | |
|19 |Replace the #2 fan control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|20 |Inspect the following components for a short to ground: |-- |Go to Electric |Go to Step 26 |
| |The mode control relay switch feed circuit (504)--Refer to Wiring | |Cooling Fan | |
| |Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you find and correct the condition? | | | |
|21 |Replace the fan motor. Refer to Engine Cooling Fan Replacement in |-- |Go to Electric |-- |
| |Engine Cooling. | |Cooling Fan | |
| |Did you complete the replacement? | |Diagnosis | |
| | | |Functional Check | |
|22 |Replace the #1 fan control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|23 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The left fan feed circuit (409)--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|24 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The mode control relay switch feed circuit (504)--Refer to Wiring | |Cooling Fan | |
| |Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|25 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The left fan control circuit--Refer to Wiring Repairs in Wiring | |Cooling Fan | |
| |Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
|26 |Replace mode control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|27 |WARNING |-- |Go to Electric |-- |
| | | |Cooling Fan | |
| |Important: The replacement PCM must be programmed. | |Diagnosis | |
| | | |Functional Check | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
Electric Cooling Fan Table #3
|Step |Action |Values |Yes |No |
|1 |Did you perform the Electric Cooling Fan Functional Check? |-- |Go to Step 2 |Go to Electric |
| | | | |Cooling Fan |
| | | | |Diagnosis |
| | | | |Functional Check |
|2 |With a scan tool, command the Low Speed Fans ON. |-- |Go to Step 8 |Go to Step 3 |
| |Command the High Speed Fans ON while observing the fans. | | | |
| |Did both fans operate with no change? | | | |
|3 |Did the left fan stop operating? |-- |Go to Step 9 |Go to Step 4 |
|4 |Disconnect the #2 fan control relay. |-- |Go to Step 5 |Go to Step 12 |
| |Probe the right fan control circuit (473) at the #2 fan control relay | | | |
| |connector terminal (85) using a test lamp that is connected to battery| | | |
| |positive voltage. | | | |
| |Using a scan tool, command the High Speed Fans ON . | | | |
| |Does the test lamp illuminate after several seconds? | | | |
|5 |Probe the coil feed circuit at #2 fan control relay connector terminal|-- |Go to Step 6 |Go to Step 13 |
| |(86) using a test lamp that is connected to ground. | | | |
| |Does the test lamp illuminate? | | | |
|6 |Probe the switch feed circuit (2340) at the #2 fan control relay |-- |Go to Step 7 |Go to Step 14 |
| |connector terminal (30) using a test lamp that is connected to ground.| | | |
| |Does the test lamp illuminate? | | | |
|7 |Jumper the switch feed circuit (2340) and the right fan feed circuit |-- |Go to Step 15 |Go to Step 16 |
| |(532) together at the #2 fan control relay connector terminals 30 and | | | |
| |87. | | | |
| |Is the right fan ON? | | | |
|8 |Turn OFF the ignition. |-- |Go to Step 22 |Go to Step 17 |
| |Disconnect the PCM. | | | |
| |Disconnect the #1 fan control relay. | | | |
| |Jumper the switch feed circuit (742) and the left fan feed circuit | | | |
| |(409) together at the #1 fan control relay connector terminals 30 and | | | |
| |87. | | | |
| |Turn ON the ignition. | | | |
| |Probe the right fan control circuit (473) at the PCM harness connector| | | |
| |with a test lamp that is connected to ground. | | | |
| |Do the fans switch from low to high speed? | | | |
|9 |Disconnect mode control relay. |-- |Go to Step 10 |Go to Step 18 |
| |Probe the right fan control circuit (473) at the mode control relay | | | |
| |connector terminal (86) using a test lamp that is connected to battery| | | |
| |positive voltage. | | | |
| |Using a scan tool, command the High Speed Fans ON. | | | |
| |Does the test lamp illuminate? | | | |
|10 |Probe the ground circuit (450) at the mode control relay connector |-- |Go to Step 11 |Go to Step 19 |
| |terminal (87) using a test lamp that is connected to battery positive | | | |
| |voltage. | | | |
| |Does the test lamp illuminate? | | | |
|11 |Probe the coil feed circuit at the mode control relay connector |-- |Go to Step 20 |Go to Step 21 |
| |Terminal (85) using a test lamp that is connected to a ground. | | | |
| |Does the test lamp illuminate? | | | |
|12 |Inspect the following components for an open between fan #2 fan |-- |Go to Electric |-- |
| |control relay and the splice: | |Cooling Fan | |
| |The right fan control circuit (473)--Refer to Wiring Repairs in Wiring| |Diagnosis | |
| |Systems. | |Functional Check | |
| |Ground splice pack--Refer to Engine Controls Component Views Ground | | | |
| |Splice Pack . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|13 |Inspect the following components for an open : |-- |Go to Electric |-- |
| |The #2 fan control relay coil feed circuit--Refer to Wiring Repairs in| |Cooling Fan | |
| |Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the replacement? | | | |
|14 |Inspect the following components for an open or short to ground: |-- |Go to Electric |-- |
| |The #2 fan control relay switch feed circuit (2340)--Refer to Wiring | |Cooling Fan | |
| |Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the replacement? | | | |
|15 |Replace the #2 fan control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|16 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The right fan feed circuit (532) between #2 fan control relay and the | |Cooling Fan | |
| |splice--Refer to Wiring Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|17 |Inspect the following components for an open or short to battery |-- |Go to Electric |-- |
| |positive voltage: | |Cooling Fan | |
| |The right fan control circuit (473)--Refer to Wiring Repairs in Wiring| |Diagnosis | |
| |Systems. | |Functional Check | |
| |Underhood junction block--Refer to Engine Controls Component Views | | | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|18 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The right fan control circuit (473) between mode control relay and the| |Cooling Fan | |
| |splice--Refer to Wiring Repairs in Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|19 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |Ground circuit (450)--Refer to Wiring Repairs in Wiring Systems. | |Cooling Fan | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Diagnosis | |
| |Underhood Junction Block . | |Functional Check | |
| |Ground splice back--Refer to Engine Controls Component Views Ground | | | |
| |Splice Pack | | | |
| |Repair as needed. | | | |
| |Did you complete the repair? | | | |
|20 |Replace the mode control relay. |-- |Go to Electric |-- |
| |Did you complete the replacement? | |Cooling Fan | |
| | | |Diagnosis | |
| | | |Functional Check | |
|21 |Inspect the following components for an open: |-- |Go to Electric |-- |
| |The mode control relay coil feed circuit--Refer to Wiring Repairs in | |Cooling Fan | |
| |Wiring Systems. | |Diagnosis | |
| |Underhood junction block--Refer to Engine Controls Component Views | |Functional Check | |
| |Underhood Junction Block . | | | |
| |Repair as needed. | | | |
| |Did you complete the replacement? | | | |
|22 |Inspect the PCM connector for poor, and intermittent connections. |-- |Go to Electric |Go to Step 23 |
| |Refer to Testing for Intermittent Conditions and Poor Connections , | |Cooling Fan | |
| |and Connector Repairs in Wiring Systems. | |Diagnosis | |
| |Did you find and correct the condition? | |Functional Check | |
|23 |WARNING |-- |Go to Electric |-- |
| | | |Cooling Fan | |
| |Important : The replacement PCM must be programmed. | |Diagnosis | |
| | | |Functional Check | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.4L > Engine Cooling Fan Description - Electric
Engine Cooling Fan Description - Electric
|NOTE |
|Applicable vehicles: |
|Alero, Grand Am (VIN N) |
Engine Cooling Fan Description - Electric
The electric cooling fans are used to lower the temperature of the engine coolant flowing through the radiator. They are also used to cool the refrigerant (R-134a) flowing through the A/C condenser.
|[pic] |
| |
| |
|Click to Enlarge |
Operation
The electric cooling fans operate when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the PCM. The cooling fan has one speed. The PCM turns the cooling fan ON by grounding the coil of the cooling fan relay when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
Power for the cooling fan motors are supplied through Cool Fan #1 and Cool Fan #2 fuses. The cooling fan relays are energized when current flows from the fuses in the Underhood Junction Block , and through the relay coils to ground through the PCM. The LH Fan Control circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The RH Fan Control circuit is grounded for high speed operation. During high speed fans operation, both fans run at high speed.
|WARNING |
|Important: When certain Diagnostic Trouble Codes (DTCs) are present, the PCM may command the cooling fans to run all the time. It |
|is important to perform Powertrain On Board Diagnostic (OBD) System Check prior to diagnosing the engine cooling fans. |
|WARNING |
|If a problem that involves the LH Fan Control circuit exists, DTC P0480 should set. If the problem affects the RH Fan Control |
|circuit, DTC P0481 should set. A problem with the ECT sensor should set DTC P0117, P0118, P1114, or P1115. Any of these DTCs may |
|affect cooling fan operation and should be diagnosed before using the Cooling Fan Diagnosis tables. The Cooling Fan Diagnosis |
|tables should be used to diagnose the PCM controlled cooling fans only, if a DTC has not set. |
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[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.4L > DTC P0480 Cooling Fan Relay 1 Control Circuit
DTC P0480 Cooling Fan Relay 1 Control Circuit
|NOTE |
|Applicable vehicles: |
|Alero, Grand Am (VIN N) |
DTC P0480 Cooling Fan Relay 1 Control Circuit
Refer to Engine Controls Schematic Cooling Fans .
Circuit Description
Output driver modules (ODMs) are used by the powertrain control module (PCM) to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding ON. ODMs have the capability of diagnosing each output circuit individually. DTC P0480 set indicates an improper voltage level has been detected on the output circuit which controls the #1 Fan Control Relay.
Conditions for Running the DTC
• The ignition is ON.
• The ignition voltage is between 9.0-18.0 volts.
Conditions for Setting the DTC
• An improper voltage level has been detected on the output circuit which controls the low-speed fans.
• The above condition is present for at least 30 seconds.
Action Taken When the DTC Sets
• The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
• The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.
Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
• The DTC can be cleared by using a scan tool.
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
|WARNING |
|Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when |
|diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion. |
• Loose terminal connection
o Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
o Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
1. The Powertrain On Board Diagnostic (OBD) System Check prompts you to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool.
2. Listen for a click when the relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. This step tests for voltage at the coil feed side of the relay.
4. This step verifies that the PCM is providing ground to the relay.
5. This step tests if ground is constantly being applied to the relay.
12. The PCM utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
|Step |Action |Values |Yes |No |
|1 |Did you perform the Powertrain On Board Diagnostic (OBD) System |-- |Go to Step 2 |Go to Powertrain On |
| |Check? | | |Board Diagnostic (OBD) |
| | | | |System Check |
|2 |Turn ON the ignition, with the engine OFF. |-- |Go to Diagnostic |Go to Step 3 |
| |With a scan tool, command the Fan relay 1 ON and OFF. | |Aids | |
| |Does the relay turn ON and OFF with each command? | | | |
|3 |Turn OFF the ignition. |-- |Go to Step 4 |Go to Step 10 |
| |Disconnect the #1 Fan relay. | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |Probe the coil feed circuit of the relay with a test lamp that is | | | |
| |connected to a good ground. | | | |
| |Does the test lamp illuminate? | | | |
|4 |Connect a test lamp between the control circuit of the relay and |-- |Go to Step 8 |Go to Step 5 |
| |the coil feed circuit of the relay. | | | |
| |With a scan tool, command the Fan relay 1 ON and OFF . | | | |
| |Does the test lamp turn ON and OFF with each command? | | | |
|5 |Does the test lamp remain illuminated with each command? |-- |Go to Step 7 |Go to Step 6 |
|6 |Test the control circuits of the relay for a short to voltage or |-- |Go to Step 13 |Go to Step 9 |
| |an open. Refer to Wiring Repairs in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|7 |Test the control circuits of the relay for a short to ground. |-- |Go to Step 13 |Go to Step 9 |
| |Refer to Wiring Repairs in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|8 |Inspect for faulty connections at the relay. Refer to Testing for |-- |Go to Step 13 |Go to Step 11 |
| |Intermittent Conditions and Poor Connections and Connector Repairs| | | |
| |in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|9 |Inspect for faulty connections at the PCM. Refer to Testing for |-- |Go to Step 13 |Go to Step 12 |
| |Intermittent Conditions and Poor Connections and Connector Repairs| | | |
| |in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|10 |Repair the feed circuit of the relay, or replace the under hood |-- |Go to Step 13 |-- |
| |Junction Block as necessary. Refer to Wiring Repairs in Wiring | | | |
| |Systems. | | | |
| |Is the action complete? | | | |
|11 |Replace the #1 Fan relay. |-- |Go to Step 13 |-- |
| |Did you complete the replacement? | | | |
|12 |WARNING |-- |Go to Step 13 |-- |
| | | | | |
| |Important: The replacement PCM must be programmed. | | | |
| | | | | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
|13 |Use the scan tool in order to clear the DTCs . |-- |Go to Step 2 |System OK |
| |Operate the vehicle within the Conditions for Running the DTC as | | | |
| |specified in the supporting text. | | | |
| |Does the DTC reset? | | | |
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[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.4L > DTC P0481Cooling Fan Relay 2 Control Circuit
DTC P0481Cooling Fan Relay 2 Control Circuit
|NOTE |
|Applicable vehicles: |
|Alero, Grand Am (VIN N) |
DTC P0481Cooling Fan Relay 2 Control Circuit
Refer to Engine Controls Schematic Cooling Fans .
Circuit Description
Output driver modules (ODMs) are used by the powertrain control module (PCM) to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding ON. ODMs have the capability of diagnosing each output circuit individually. DTC P0481 set indicates an improper voltage level has been detected on the on the output circuit which controls the Mode Control and #2 Fan Control Relays.
Conditions for Running the DTC
• The ignition is ON.
• The ignition voltage is between 9.0-18.0 volts.
Conditions for Setting the DTC
• An improper voltage level has been detected on the output circuit which controls the high speed fans.
• The above condition is present for at least 30 seconds.
Action Taken When the DTC Sets
• The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
• The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.
Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
• The DTC can be cleared by using a scan tool.
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
|WARNING |
|Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when |
|diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion. |
• Loose terminal connection
o Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
o Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
1. The Powertrain On Board Diagnostic (OBD) System Check prompts you to complete some basic tests and store the Freeze Frame and Failure Records data on the scan tool.
2. Listen for a click when the relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. This step tests for voltage at the coil feed side of the relays.
4. This step verifies that the PCM is providing ground to the relays.
5. This step tests if ground is constantly being applied to the relays.
12. The PCM utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
|Step |Action |Values |Yes |No |
|1 |Did you perform the Powertrain On Board Diagnostic (OBD) System |-- |Go to Step 2 |Go to Powertrain On |
| |Check? | | |Board Diagnostic |
| | | | |(OBD) System Check |
|2 |WARNING |-- |Go to Diagnostic |Go to Step 3 |
| | | |Aids | |
| |Important : If you cannot determine if the relays are responding to | | | |
| |the command, observe the fans. When FAN 2 is commanded ON, both fans | | | |
| |should operate in low speed and after several seconds both fans | | | |
| |should switch to high speed. If the fans are not operating properly | | | |
| |continue with step 3 of this table. | | | |
| | | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |With a scan tool, command the Fan relay 2 and 3 ON and OFF. | | | |
| |Do both relays turn ON after several seconds and OFF with each | | | |
| |command? | | | |
|3 |Turn OFF the ignition. |-- |Go to Step 4 |Go to Step 10 |
| |Disconnect the Fan 2 and Fan 3 relays. | | | |
| |Turn ON the ignition, with the engine OFF. | | | |
| |Probe the coil feed circuits of each relay with a test lamp that is | | | |
| |connected to a good ground. | | | |
| |Does the test lamp illuminate for both circuits? | | | |
|4 |Connect a test lamp between the control circuits of each relay and |-- |Go to Step 8 |Go to Step 5 |
| |the coil feed circuits of each relay. | | | |
| |With a scan tool, command the Fan relay 2 and 3 ON and OFF . | | | |
| |Does the test lamp turn ON after several seconds and OFF with each | | | |
| |command for both relays? | | | |
|5 |Does the test lamp remain illuminated with each command when probing |-- |Go to Step 7 |Go to Step 6 |
| |either feed circuit? | | | |
|6 |Test the control circuits of each relay for a short to voltage or an |-- |Go to Step 13 |Go to Step 9 |
| |open. Refer to Wiring Repairs in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|7 |Test the control circuits of each relay for a short to ground. Refer |-- |Go to Step 13 |Go to Step 9 |
| |to Wiring Repairs in Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|8 |Inspect for faulty connections at the relays. Refer to Testing for |-- |Go to Step 13 |Go to Step 11 |
| |Intermittent Conditions and Poor Connections and Connector Repairs in| | | |
| |Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|9 |Inspect for faulty connections at the PCM. Refer to Testing for |-- |Go to Step 13 |Go to Step 12 |
| |Intermittent Conditions and Poor Connections and Connector Repairs in| | | |
| |Wiring Systems. | | | |
| |Did you find and correct the condition? | | | |
|10 |Repair the feed circuit of the affected relay, or replace the under |-- |Go to Step 13 |-- |
| |hood Junction Block as necessary. Refer to Wiring Repairs in Wiring | | | |
| |Systems. | | | |
| |Did you complete the repair? | | | |
|11 |Replace the affected relay. |-- |Go to Step 13 |-- |
| |Did you complete the repair? | | | |
|12 |WARNING |-- |Go to Step 13 |-- |
| | | | | |
| |Important: The replacement PCM must be programmed. | | | |
| | | | | |
| |Replace the PCM. Refer to Powertrain Control Module | | | |
| |Replacement/Programming . | | | |
| |Did you complete the replacement? | | | |
|13 |Use the scan tool in order to clear the DTCs . |-- |Go to Step 2 |System OK |
| |Operate the vehicle within the Conditions for Running the DTC as | | | |
| |specified in the supporting text. | | | |
| |Does the DTC reset? | | | |
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