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Contents Wiring diagrams Section: Cooling Fan All sections

Electric Cooling Fan Chevrolet Impala VIII

Cooling Fan 12 illustrations ~6294 words

MODEL IDENTIFICATION

WARNINGVehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see AIR BAG SAFETY PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS.
CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.
ModelBody Code (1)
Chevrolet
ImpalaW
Monte CarloW
(1) Vehicle body code is 4th character of VIN.
(1)Vehicle body code is 4th character of VIN.

MODEL IDENTIFICATION

3.4L Engine

The engine cooling fans are controlled by the Body Control Module (BCM) and the Powertrain Control Module (PCM). The BCM sends a Class 2 message to the PCM requesting cooling fan operation. If there is a Class 2 communication malfunction between the BCM and the PCM. The PCM will operate the engine cooling fans independently of the BCM.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the PCM to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the engine wiring harness junction block. The ground path is provided at G101.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan one relay coil, closes the relay contacts, and supplies battery positive voltage from the FAN CONT #1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan one relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage from the FAN CONT #2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The BCM will request low speed cooling fan operation from the PCM under the following conditions

  1. Engine coolant temperature exceeds approximately 217°F (103°C).
  2. When A/C is requested and the ambient temperature is more than 122°F (50°C).
  3. A/C refrigerant pressure exceeds 190 psi (1310 kPa).
  4. After the vehicle is shut off if the engine coolant temperature at key-off is more than 243°F (117°C) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The BCM will request high speed cooling fan operation from the PCM under the following conditions

  1. Engine coolant temperature reaches 230°F (110°C).
  2. A/C refrigerant pressure exceeds 240 psi (1655 kPa).
  3. When certain DTCs set.

3.8L Engine

The engine cooling fans are controlled by the Body Control Module (BCM) and the Powertrain Control Module (PCM). The BCM sends a Class 2 message to the PCM requesting cooling fan operation. If there is a Class 2 communication malfunction between the BCM and the PCM. The PCM will operate the engine cooling fans independently of the BCM.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the PCM to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the engine wiring harness junction block. The ground path is provided at G101.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan one relay coil, closes the relay contacts, and supplies battery positive voltage from the FAN CONT #1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan one relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage from the FAN CONT #2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The BCM will request low speed cooling fan operation from the PCM under the following conditions

  1. Engine coolant temperature exceeds approximately 212°F (100°C).
  2. When A/C is requested and the ambient temperature is more than 50°F (10°C).
  3. A/C refrigerant pressure exceeds 190 psi (1310 kPa).
  4. After the vehicle is shut off if the engine coolant temperature at key-off is more than 243°F (117°C) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The BCM will request high speed cooling fan operation from the PCM under the following conditions

  1. Engine coolant temperature reaches 221°F (105°C).
  2. A/C refrigerant pressure exceeds 240 psi (1655 kPa).
  3. When certain DTCs set.

COMPONENT LOCATIONS

ComponentLocation
Cooling Fans (1)Underhood Behind Radiator
Cooling Fan Fuses & Relays (2)In Bottom Underhood Fuse Block At Front Passengers Side
(1) (Scheme 1) (2) (Scheme 2)and (Scheme 3).

COMPONENT LOCATIONS

Scheme 1

Scheme 1
Scheme 1

Scheme 2

Scheme 2
Scheme 2

Scheme 3

Scheme 3
Scheme 3

PROGRAMMING

Note. For programming of separate modules or components, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

POWERTRAIN CONTROL MODULE

These models use the Service Programming System (SPS) to reprogram the PCM and other modules. The SPS allows a technician to program a control module through the Data Link Connector (DLC). See POWERTRAIN CONTROL MODULE for 3.4L engines or POWERTRAIN CONTROL MODULE for 3.8L engines under PROGRAMMING in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.

PRELIMINARY INSPECTION

Verify customer complaint by operating suspecting system. Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. For Impala fuse and/or relay identification, see FUSES & CIRCUIT BREAKERS article in ELECTRICAL. For Monte Carlo fuse and/or relay identification, see FUSES & CIRCUIT BREAKERS article in ELECTRICAL.

Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If no fault is found, perform self-diagnostics. See SELF-DIAGNOSTIC SYSTEM .

RETRIEVING DIAGNOSTIC TROUBLE CODES

See RETRIEVING DIAGNOSTIC TROUBLE CODES for 3.4L engine or RETRIEVING DIAGNOSTIC TROUBLE CODES for 3.8L engine under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.

CLEARING DIAGNOSTIC TROUBLE CODES

See CLEARING DIAGNOSTIC TROUBLE CODES for 3.4L engine or CLEARING DIAGNOSTIC TROUBLE CODES for 3.8L engine under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.

DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)

  1. Install a scan tool. Does the scan tool power up? If so, proceed to next step. If not, see «TEST D: SCAN TOOL DOES NOT POWER UP»(/chevrolet/impala/viii-1999-2006/remont/communication-devices/#body-control-modules__test-d-scan-tool-does-not) under SYSTEM TESTS in BODY CONTROL MODULES article in COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
  2. Turn on the ignition, with the engine off. Attempt to establish communication with the instrument cluster and the powertrain control module. Does the scan tool communicate with the control modules? If so, proceed to next step. If not, see «TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE»(/chevrolet/impala/viii-1999-2006/remont/communication-devices/#body-control-modules) under SYSTEM TESTS in BODY CONTROL MODULES article in COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
  3. Select the powertrain control module display DTCs function on the scan tool. Does the scan tool display any DTCs? If so, proceed to next step. If not, see «SYMPTOMS (ENGINE COOLING)»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__symptoms-engine-cooling) .
  4. Does the scan tool display any DTCs which begin with a "U"? If so, see «TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE»(/chevrolet/impala/viii-1999-2006/remont/communication-devices/#body-control-modules) under SYSTEM TESTS in BODY CONTROL MODULES article in COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT. If not, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-trouble-code-definitions) .

SYMPTOMS (ENGINE COOLING)

Note. Review the system operation in order to familiarize yourself with the system functions. See DESCRIPTION & OPERATION .

Note. After visual/physical inspection and intermittent inspection, see SYMPTOM INDEX table under SYSTEM TESTS to diagnose a symptom.

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the Cooling System. See «CHECKING AFTERMARKET ACCESSORIES»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
  3. Inspect the surge tank reservoir for the proper coolant level.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions.

CHECKING AFTERMARKET ACCESSORIES

Do not connect aftermarket accessories into the following circuits

  1. SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol.
  2. OBD II circuits, all such circuits are indicated on circuit diagrams with the OBD II symbol.

Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems.

Possible causes of vehicle problems related to aftermarket accessories include

  1. Power feeds connected to points other than the battery.
  2. Antenna location.
  3. Transceiver wiring located too close to vehicle electronic modules or wiring.
  4. Poor shielding or poor connectors on antenna feed line.
  5. Check for recent service bulletins detailing installation guidelines for aftermarket accessories.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DTC (1)Description
P0480Low Speed Cooling Fan Relay Control Circuit Improper Voltage Level
P0481High Speed Cooling Fan Relay Control Circuit Improper Voltage Level
(1) Perform appropriate test under DIAGNOSTIC TESTS . Codes listed in this table are only for testing covered in this article. For a complete list of codes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.
(1)Perform appropriate test under DIAGNOSTIC TESTS . Codes listed in this table are only for testing covered in this article. For a complete list of codes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Circuit Description

Battery positive voltage is supplied to the cooling fan one relay from the FAN CONT #1 fuse. The Powertrain Control Module (PCM) controls the cooling fan one relay by grounding the low speed cooling fan relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low (near zero volts). When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following

  1. A short to ground.
  2. A short to voltage.
  3. An open circuit.
  4. An open relay coil.
  5. An internally shorted or excessively low resistance relay coil.

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

Conditions For Running DTC

  1. The ignition is on.
  2. System voltage is 9-18 volts.

Conditions For Setting DTC

  1. An improper voltage level has been detected on the low speed cooling fan relay control circuit.
  2. The above conditions are present for at least 30 seconds.

Action Taken When DTC Sets

  1. The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
  2. The PCM will store conditions which were present when the DTC set as freeze frame and failure records data.

Conditions For Clearing MIL/DTC

  1. The PCM will turn off the MIL during the third consecutive trip in which the diagnostic has been run and passed.
  2. The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
  3. The DTC can be cleared by using the scan tool.

Diagnostic Aids

  1. If the condition is not present, test for intermittent and poor connections.
  2. Review the freeze/failure records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Testing

Note. To identify system wiring schematics, see WIRING DIAGRAMS .

Note. When checking or testing a connector end view, see CONNECTOR IDENTIFICATION .

  1. Did you perform the DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)? If so, proceed to next step. If not, see «DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-system-check-engine-cooling) under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn on the ignition, with the engine off. With a scan tool, command the fans low speed ON and OFF. Does the cooling fan one relay turn on and off with each command? If so, see «DIAGNOSTIC AIDS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-aids) . If not, proceed to next step.
  3. Turn off the ignition. Disconnect the cooling fan one relay. Turn on the ignition, with the engine off. Probe the battery positive voltage circuit of the cooling fan one relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, proceed to next step. If not, go to step 8 .
  4. Connect a test lamp between the control circuit of the cooling fan one relay and the battery positive voltage circuit of the cooling fan one relay. With a scan tool, command the fans low speed ON and OFF. Does the test lamp turn on and off with each command? If so, go to step 10 . If not, proceed to next step.
  5. Does the test lamp remain illuminated with each command? If so, go to step 7 . If not, proceed to next step.
  6. Test the control circuit of the cooling fan one relay for a short to voltage or an open. Did you find and correct the condition? If so, go to step 14 . If not, go to step 9 .
  7. Test the control circuit of the cooling fan one relay for a short to ground. Did you find and correct the condition? If so, go to step 14 . If not, go to step 9 .
  8. Test the battery positive voltage circuit of the cooling fan one relay for a short to ground or an open. Did you complete the repair? If so, go to step 14 . If not, go to step 11 .
  9. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step 14 . If not, go to step 13 .
  10. Inspect for poor connections at the cooling fan one relay. Did you find and correct the condition? If so, go to step 14 . If not, go to step 12 .
  11. Repair the cooling fan motor supply voltage circuit for a short to ground. When complete, go to step 14 .
  12. Replace the cooling fan one relay. When complete, go to step 14 .
  13. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(/chevrolet/impala/viii-1999-2006/remont/communication-devices/#body-control-modules) under REMOVAL & INSTALLATION in BODY CONTROL MODULES article in COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
  14. Use the scan tool in order to clear the DTCs. Operate the vehicle within the conditions for running the DTC as specified in the supporting text. Does the DTC reset? If so, go to step 2 . If not, system is okay.

Battery positive voltage is supplied to the cooling fan 2 relay and the cooling fan 3 relay from the FAN CONT #2 and FAN CONT #3 fuse. The Powertrain Control Module (PCM) controls the relays by grounding the high speed cooling fan relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low (near zero volts). When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following

  1. A short to ground.
  2. A short to voltage.
  3. An open circuit.

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

  1. The ignition is on.
  2. The system voltage is 9 and 18 volts.
  1. An improper voltage level has been detected on the high speed cooling fan relay control circuit.
  2. The above conditions are present for at least 30 seconds.
  1. The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
  2. The PCM will store conditions which were present when the DTC set as freeze frame and failure records data.
  1. The PCM will turn off the MIL during the third consecutive trip in which the diagnostic has been run and passed.
  2. The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
  3. The DTC can be cleared by using the scan tool.
  1. If the condition is not present, testing for intermittent and poor connections.
  2. Review the freeze/failure records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Note. To identify system wiring schematics, see WIRING DIAGRAMS .

Note. When checking or testing a connector end view, see CONNECTOR IDENTIFICATION .

  1. Did you perform the DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)? If so, proceed to next step. If not, see «DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-system-check-engine-cooling) under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn on the ignition, with the engine off. With a scan tool, command the fans high speed ON and OFF. Does the cooling fan 2 and the cooling fan 3 relays turn on and off with each command? If so, see «DIAGNOSTIC AIDS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan) . If not, proceed to next step.
  3. Turn off the ignition. Disconnect the cooling fan 3 relay. Turn on the ignition, with the engine off. Probe the battery positive voltage circuit of the cooling fan 3 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, proceed to next step. If not, go to step 8 .
  4. Connect a test lamp between the control circuit of the cooling fan 3 relay and the battery positive voltage circuit of the cooling fan 3 relay. With a scan tool, command the fans high speed ON and OFF. Does the test lamp turn on and off with each command? If so, go to step 9 . If not, proceed to next step.
  5. Does the test lamp remain illuminated with each command? If so, go to step 7 . If not, proceed to next step.
  6. Test the control circuit of the cooling fan 2 relay and the cooling fan 3 relay for a short to voltage or an open. Did you find and correct the condition? If so, go to step 12 . If not, go to step 9 .
  7. Test the control circuit of the cooling fan 2 relay and the cooling fan 3 relay for a short to ground. Did you find and correct the condition? If so, go to step 12 . If not, go to step 9 .
  8. Test the battery positive voltage circuit of the cooling fan 2 relay and the cooling fan 3 relay for an open or a short to ground. Did you find and correct the condition? If so, go to step 12 . If not, go to step 10 .
  9. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step 12 . If not, go to step 11 .
  10. Repair the cooling fan motor supply voltage circuit for a short to ground. When complete, go to step 12 .
  11. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(/chevrolet/impala/viii-1999-2006/remont/communication-devices/#body-control-modules) under REMOVAL & INSTALLATION in BODY CONTROL MODULES article in COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT. When complete, proceed to next step.
  12. Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? If so, go to step 2 . If not, system is okay.

SYSTEM TESTS

SymptomTest
Cooling Fan Always OnA
Cooling Fan InoperativeB

SYMPTOM INDEX

TEST A: COOLING FAN ALWAYS ON

Note. This symptom occurs when one or both engine cooling fan motors run continuously in high or low speed modes.

Note. To identify system wiring schematics, see WIRING DIAGRAMS .

Note. When checking or testing a connector end view, see CONNECTOR IDENTIFICATION .

  1. Did you perform the DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)? If so, proceed to next step. If not, see «DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-system-check-engine-cooling) under SELF-DIAGNOSTIC SYSTEM.
  2. Turn on the ignition, with the engine off. Are one or both cooling fans on? If so, proceed to next step. If not, test system for intermittent and poor connections.
  3. Are both cooling fans running continuously? If so, go to step 5 . If not, proceed to next step.
  4. Remove the FAN CONT #2 relay. Did the left cooling fan turn off? If so, go to step 8 . If not, go to step 6 .
  5. Remove the FAN CONT #1 relay. Did the cooling fans turn off? If so, go to step 10 . If not, go to step 7 .
  6. Remove the FAN CONT #3 relay. Did the left cooling fan turn off? If so, go to step 11 . If not, go to step 9 .
  7. Repair the short to voltage in the right cooling fan motor supply voltage circuit. When complete, go to step 14 .
  8. Repair the short to voltage in the right cooling fan low reference circuit. When complete, go to step 14 .
  9. Repair the short to voltage in the left cooling fan motor supply voltage circuit. When complete, go to step 14 .
  10. Inspect for poor connections at the FAN CONT #1 relay. Did you find and correct the condition? If so, go to step 14 . If not, go to step 12 .
  11. Inspect for poor connections at the FAN CONT #3 relay. Did you find and correct the condition? If so, go to step 14 . If not, go to step 13 .
  12. Replace the FAN CONT #1 relay. When complete, go to step 14 .
  13. Replace the FAN CONT #3 relay. When complete, proceed to next step.
  14. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 2 .

TEST B: COOLING FAN INOPERATIVE

Note. This symptom occurs when one or both engine cooling fan motors do not operate properly in high or low speed modes.

Note. To identify system wiring schematics, see WIRING DIAGRAMS .

Note. When checking or testing a connector end view, see CONNECTOR IDENTIFICATION .

  1. Did you perform the DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)? If so, proceed to next step. If not, see «DIAGNOSTIC SYSTEM CHECK (ENGINE COOLING)»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__diagnostic-system-check-engine-cooling) under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn on ignition, with engine off. With a scan tool, command the low speed fan ON and OFF. Do the low speed engine cooling fans turn on and off with each command? If so, proceed to next step. If not, go to step 4 .
  3. With a scan tool, command the fans high speed ON and OFF. Do the high speed engine cooling fans turn on and off with each command? If so, test for intermittent and poor connections. If not, go to step 12 .
  4. Remove the cooling fan one relay. Connect a 20-amp fused jumper between the battery positive switch side voltage circuit and the cooling fan motor supply voltage circuit of the cooling fan one relay. Do both cooling fans operate in low speed? If so, go to step 22 . If not, proceed to next step.
  5. Disconnect the cooling fan 2 relay. Connect the second 20-amp fused jumper between the cooling fan low reference circuit and the cooling fan motor supply voltage circuit of the cooling fan 2 relay. Do both cooling fans operate in low speed? If so, go to step 23 . If not, proceed to next step.
  6. Connect the second 20-amp fused jumper between the battery positive voltage circuit and the cooling fan motor supply voltage circuit of the cooling fan 2 relay. Does the left cooling fan operate in high speed? If so, go to step 9 . If not, proceed to next step.
  7. Install the cooling fan 2 relay. Disconnect the left cooling fan electrical connector. Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit to the ground circuit of the left cooling fan electrical connector. Does the right cooling fan operate in high speed? If so, go to step 25 . If not, proceed to next step.
  8. Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit of the left cooling fan electrical connector to a good ground. Does the right cooling fan operate in high speed? If so, go to step 29 . If not, go to step 30 .
  9. Install the cooling fan 2 relay. Disconnect the right cooling fan electrical connector. Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit to the cooling fan low reference circuit of the right cooling fan electrical connector. Does the left cooling fan operate in high speed? If so, go to step 26 . If not, proceed to next step.
  10. Connect the second 20-amp fused jumper wire from the coil side battery positive voltage circuit to the cooling fan low reference circuit of the of the right cooling fan electrical connector. Does the left cooling fan operate in high speed? If so, proceed to next step. If not, go to step 31 .
  11. Probe the battery positive voltage circuit on the switch side of the cooling fan one relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, go to step 27 . If not, go to step 32 .
  12. Is the left cooling fan operating properly in high speed? If so, go to step 19 . If not, proceed to next step.
  13. Turn off the ignition. Disconnect the cooling fan 3 relay. Turn on the ignition, with the engine off. Connect a test lamp between the high speed cooling fan relay control circuit and the battery positive voltage circuit on the coil side of the cooling fan 3 relay. With a scan tool command the high speed fans ON and OFF. Does the test lamp turn on and off with each command? If so, go to step 15 . If not, proceed to next step.
  14. Probe the battery positive voltage circuit on the coil side of the cooling fan 3 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, go to step 34 . If not, go to step 33 .
  15. Install a 20-amp fused jumper between the battery positive voltage circuit on the switch side of the cooling fan 3 relay and the cooling fan motor supply voltage circuit. Does the left cooling fan operate in high speed? If so, go to step 24 . If not, proceed to next step.
  16. Probe the battery positive voltage circuit on the switch side of the cooling fan 3 relay with a test lamp connected to a good ground. Does the test lamp illuminate? If so, proceed to next step. If not, go to step 33 .
  17. With the 20-amp fused jumper still installed. Disconnect the left cooling fan electrical connector. Connect a test lamp from the cooling fan motor supply voltage circuit to the ground circuit of the left cooling fan electrical connector. Does the test lamp illuminate? If so, go to step 25 . If not, proceed to next step.
  18. Probe the cooling fan motor supply voltage circuit of the left cooling fan electrical connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, go to step 29 . If not, go to step 30 .
  19. Turn off the ignition. Disconnect the cooling fan 2 relay Turn on the ignition, with the engine off. Connect a 20-amp fused jumper between the cooling fan low reference circuit and the ground circuit of the cooling fan 2 relay. With a scan tool command the fans high speed ON and OFF. Does the right cooling fan operate in high speed? If so, proceed to next step. If not, go to step 28 .
  20. Connect a test lamp between the high speed cooling fan relay control circuit of the cooling fan 2 relay and the battery positive voltage circuit of the cooling fan 2 relay. With a scan tool command the fans high speed ON and OFF. Does the test lamp turn on and off with each command? If so, go to step 23 . If not, proceed to next step.
  21. Probe the battery positive voltage circuit of the cooling fan 2 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? If so, go to step 34 . If not, go to step 33 .
  22. Inspect for poor connections at the cooling fan one relay. Did you find and correct the condition? If so, go to step 40 . If not, go to step 35 .
  23. Inspect for poor connections at the cooling fan 2 relay. Did you find and correct the condition? If so, go to step 40 . If not, go to step 36 .
  24. Inspect for poor connections at the cooling fan 3 relay. Did you find and correct the condition? If so, go to step 40 . If not, go to step 37 .
  25. Inspect for poor connections at the harness connector of the left cooling fan. Did you find and correct the condition? If so, go to step 40 . If not, go to step 38 .
  26. Inspect for poor connections at the harness connector of the right cooling fan. Did you find and correct the condition? If so, go to step 40 . If not, go to step 39 .
  27. Repair the right cooling fan motor supply voltage circuit for an open. When complete, go to step 40 .
  28. Repair the right cooling fan ground circuit for an open. When complete, go to step 40 .
  29. Repair the left cooling fan ground circuit for an open. When complete, go to step 40 .
  30. Repair the left cooling fan motor supply voltage circuit for an open. When complete, go to step 40 .
  31. Repair the right cooling fan low reference circuit for a short to ground or an open. When complete, go to step 40 .
  32. Repair the cooling fan one relay battery positive voltage circuit for an open. When complete, go to step 40 .
  33. Repair the battery positive voltage circuit for the cooling fan 2 and 3 relay for an open. When complete, go to step 40 .
  34. Repair the high speed cooling fan relay control circuit for an open. When complete, go to step 40 .
  35. Replace the cooling fan one relay. When complete, go to step 40 .
  36. Replace the cooling fan 2 relay. When complete, go to step 40 .
  37. Replace the cooling fan 3 relay. When complete, go to step 40 .
  38. Replace the left cooling fan. See «FAN SHROUD»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__fan-shroud) under REMOVAL & INSTALLATION. When complete, go to step 40 .
  39. Replace the right cooling fan. See «FAN SHROUD»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__fan-shroud) under REMOVAL & INSTALLATION. When complete, proceed to next step.
  40. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 3 .

REMOVAL & INSTALLATION

WARNINGVehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see AIR BAG SAFETY PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS.
CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.
CAUTIONUse the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

FAN SHROUD

WARNINGBefore servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be off, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

Scheme 4

Scheme 4: Removal
Scheme 4: Removal

Scheme 5

Scheme 5
Scheme 5

Scheme 6

Scheme 6
Scheme 6

Scheme 7

Scheme 7
Scheme 7

Scheme 8

Scheme 8
Scheme 8

Scheme 9

Scheme 9
Scheme 9
  1. Disconnect the negative battery cable with the following procedures: Record all of the vehicle preset radio stations. Turn off all the lamps and the accessories. Make sure the ignition switch is in the OFF position. Disconnect the battery negative cable from the battery. (Scheme 4)
  2. Partially drain the cooling system with the following procedures: Park the vehicle on a level surface. Remove the coolant pressure cap. Raise and support the vehicle. Place a drain pan under the drain cock. Open the radiator drain cock. Drain the cooling system.
  3. Raise and support the vehicle.
  4. Remove the transmission oil cooler lines from the retainers at the bottom of the cooling fan shroud.
  5. Lower the vehicle.
  6. Remove the right and the left engine mount struts. (Scheme 5), (Scheme 6), (Scheme 7), or (Scheme 8).
  7. Remove the left front fender upper diagonal brace with the following procedures: Remove the electrical harness push-in connector from the brace. Remove the bolt from the front end sheet metal diagonal brace at the inner fender. (Scheme 9) Remove the bolts from the front end sheet metal diagonal brace at the radiator support. Remove the front end sheet metal diagonal brace.
  8. Remove the radiator inlet hose from the radiator.
  9. Remove the air cleaner assembly. (Scheme 10)and (Scheme 11).
  10. Remove the PCM harness from the fan shroud clip.
  11. If equipped remove the cooling fan heat shields.
  12. Disconnect the cooling fan shroud electrical connectors.
  13. Remove the cooling fan shroud bolts. (Scheme 12)
  14. Disengage the cooling fan shroud clip from the top of the radiator.
  15. Remove the radiator upper support brackets that connect to the fan shroud.
  16. Remove the cooling fan shroud.

Scheme 10

Scheme 10
Scheme 10

Installation

Note. Tools Required: Coolant & Battery Fluid Tester (J-23688).

  1. Install the cooling fan shroud. (Scheme 12)
  2. Install the cooling fan shroud clip to the top of the radiator. Apply pressure in order to completely engage the clip onto the radiator.
  3. Install the cooling fan shroud bolts. Tighten the bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications).
  4. Connect the cooling fan shroud electrical connectors.
  5. Install the cooling fan heat shields.
  6. Install the radiator upper support brackets and bolts that hold the fan shroud. Tighten the bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications).
  7. Install the air cleaner assembly. (Scheme 10)and (Scheme 11). Install the 2 screws into the 2 air cleaner housing sections. Tighten the screws to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications).
  8. Install the PCM harness on to the fan shroud clip.
  9. Install the radiator inlet hose to the radiator.
  10. Install the left front fender upper diagonal brace with the following procedures: Align the front end sheet metal diagonal brace to the radiator support and to the inner fender. (Scheme 9) Install the bolts to the front end sheet metal diagonal brace at the radiator support. Tighten the front end sheet metal diagonal brace at radiator support bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications). Install the bolts to the front end sheet metal diagonal brace at the inner fender. Tighten the front end sheet metal diagonal brace to the inner fender bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications). Install the electrical harness push-in connector to the brace.
  11. Install the right and left engine mount struts. (Scheme 5), (Scheme 6), (Scheme 7), or (Scheme 8). Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications).
  12. Raise the vehicle.
  13. Install the transmission oil cooler lines to the retainers at the bottom of the cooling fan shroud.
  14. Lower the vehicle.
  15. Fill the cooling system with the following procedures: Close the radiator drain cock. Tighten the radiator drain cock to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications). If the engine block drain plug was removed, apply pipe sealer to the drain plug and install the drain plug. Tighten the drain plug to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications). Lower the vehicle. Open the cooling system bleeder screws. NOTE: Use a 50/50 mixture of DEX-COOL antifreeze and deionized water. Slowly fill the cooling system with a 50/50 coolant mixture. Close the cooling system bleeder screws. Install the coolant pressure cap. Start the engine. Run the engine at 2000-2500 RPM until the engine reaches normal operating temperature. Allow the engine to idle for 3 minutes. Shut the engine off. Allow the engine to cool. Top off the coolant as necessary. Inspect the concentration of the engine coolant using the coolant and battery fluid tester. Rinse away any excess coolant from the engine and the engine compartment. Inspect the cooling system for leaks.
  16. Connect the negative battery cable with the following procedures: NOTE: Clean any existing oxidation from the contact face of the battery terminal and battery cable using a wire brush before installing the battery cable to the battery terminal. Connect the battery negative cable to the battery. (Scheme 4) Tighten the battery negative terminal bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/impala/viii-1999-2006/remont/cooling-fan/#electric-cooling-fan__torque-specifications). Program the radio stations back into the radio as recorded at the beginning of the procedure.
  17. Inspect for proper operation.

TORQUE SPECIFICATIONS

ApplicationFt. Lbs. (N.m)
Battery Negative Terminal Bolt11 (15)
Drain Plug16 (22)
Front End Sheet Metal Diagonal Brace At Radiator Support Bolts18 (25)
Front End Sheet Metal Diagonal Brace-To-Inner Fender Bolts35 (47)
Right & Left Engine Mount Strut Bolts35 (48)
INCH Lbs. (N.m)
Air Cleaner Housing Section Screws35 (4)
Cooling Fan Shroud Bolts89 (10)
Radiator Drain Cock18 (2)
Radiator Upper Support Bracket Bolts89 (10)

TORQUE SPECIFICATIONS

Scheme 11

Scheme 11: CONNECTOR IDENTIFICATION
Scheme 11: CONNECTOR IDENTIFICATION

Scheme 12

Scheme 12
Scheme 12

WIRING DIAGRAMS

Note. For Impala cooling fan wiring, see COOLING FAN in WIRING DIAGRAMS article in ELECTRICAL.

Note. For Monte Carlo cooling fan wiring, see COOLING FAN in WIRING DIAGRAMS article in ELECTRICAL.

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