Cooling Fan Inoperative
Cooling Fan Inoperative (LEA)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The engine cooling fan system is composed of one cooling fan, a series of 3 relays, the engine control module (ECM), and the associated wiring. The cooling fan motor assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits. The underhood fuse block supplies the cooling fan relays with B+ at the switch side, and ignition voltage at the coil side of the relays through separate fuses. When the cooling fan is commanded ON, the ECM grounds the appropriate relay control circuit, which energizes the relay coil. The magnetic field, created within the relay by the energized relay coil, overcomes the spring tension of the bi-metal switch armature causing the relay switch to close. When the relay switch closes, B+ is supplied to the cooling fan motor through the relay controlled output circuit, causing the cooling fan motor to operate. A dedicated ground is supplied to the cooling motor to complete the circuit.
Diagnostic Aids
* The scan tool cooling fan output control operates as follows:
- Cooling Fan Relay 1 operates the fan at a low speed
- Cooling Fan Relay 2 and 3 operates the fan at a medium speed
- Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
* When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
Reference Information
Schematic Reference
Engine Heating/Cooling Schematics [1][2]Cooling System
Connector End View Reference
* Component Connector End Views Outside Rearview Mirror - Driver
* Electrical Center Identification Views Fuse Block - Underhood Label
Description and Operation
Cooling Fan Description and Operation (LEA) Cooling Fan Description and OperationCooling Fan Description and Operation (LHU) Cooling Fan Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set.
• If a DTC is set
Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LEA) P0480.
• If no DTC is not set
3. Verify the cooling fan turns ON and operates at low, medium and high speed, when commanding the appropriate cooling fan relays ON and OFF with a scan tool.
• If the cooling fan does not operate at all speeds
Refer to Circuit/System Testing
• If the cooling fan operates at all speeds
4. All OK.
Circuit/System Testing
Inoperative in All Speeds
1. Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor.
2. Verify a test lamp illuminates between the ground circuit terminal 1 and B+.
• If the test lamp does not illuminate
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If the test lamp illuminates
3. Test or replace the G10 Cooling Fan Motor.
Low/High Speed Inoperative
1. Ignition OFF, disconnect the cooling fan relays listed below, ignition ON.
* KR20C Cooling Fan Low Speed Relay
* KR20D Cooling Fan High Speed Relay
2. Verify a test lamp illuminates between the KR20C Cooling Fan Low Speed Relay B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the B+ circuit, end to end.
• If 2 ohms or greater, repair the open/high resistance in the B+ circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the B+ circuit.
• If infinite resistance
3. Disconnect the harness connector at the G10 Cooling Fan Motor.
4. Test for infinite resistance between the relay circuit terminals listed below and ground.
* KR20D Cooling Fan High Speed Relay B+ circuit terminal 30
* KR20D Cooling Fan High Speed Relay output circuit terminal 87
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance, test or replace the G10 Cooling Fan Motor.
• If the test lamp illuminates
3. Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor.
4. Remove the test lamp and reconnect the KR20C Cooling Fan Low Speed Relay, ignition ON.
5. Command the cooling fan ON at low speed.
6. Verify a test lamp illuminates between the KR20D Cooling Fan High Speed Relay B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate
1. Ignition OFF, remove the test lamp and the KR20C Cooling Fan Low Speed Relay.
2. Test for less than 2 ohms between the KR20C Cooling Fan Low Speed Relay terminal 87 and KR20D Cooling Fan High Speed Relay terminal 30.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the KR20C Cooling Fan Low Speed Relay.
• If the test lamp illuminates
7. Ignition OFF, remove the test lamp and reconnect the KR20D Cooling Fan High Speed Relay.
8. Command the cooling fan ON at high speed with a scan tool.
9. Verify a test lamp illuminates between the G10 Cooling Fan Motor terminals listed below and ground.
* G10 Cooling Fan Motor low speed circuit terminal 2
* G10 Cooling Fan Motor high speed circuit terminal 4
• If the test lamp does not illuminate at terminal 4
1. Ignition OFF, remove the test lamp and disconnect the KR20D Cooling Fan High Speed Relay.
2. Test for less than 2 ohms in the KR20D Cooling Fan High Speed Relay output circuit terminal 87, end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the KR20D Cooling Fan High Speed Relay.
• If the test lamp does not illuminate at terminal 2
1. Ignition OFF, remove the test lamp and disconnect the KR20C Cooling Fan Low Speed Relay.
2. Test for less than 2 ohms in the KR20C Cooling Fan Low Speed Relay output circuit terminal 87, end to end.
• If 2 ohms or greater and the 30 A fuse is good, repair the open/high resistance in the output circuit.
• If 2 ohms or greater and the 30 A fuse is open, test the output circuit for a short to ground. If the circuit tests normal, test or replace the G10 Cooling Fan Motor.
• If the test lamp illuminates at both terminals
10. Test or replace the G10 Cooling Fan Motor.
Medium Speed Inoperative
1. Ignition OFF, disconnect the KR20P Cooling Fan Medium Speed Relay, ignition ON.
2. Verify a test lamp illuminates between the KR20P Cooling Fan Medium Speed Relay B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the B+ circuit terminal 30, end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance.
3. Disconnect the harness connector at the G10 Cooling Fan Motor.
4. Test for infinite resistance between the KR20P Cooling Fan Medium Speed Relay output circuit terminal 87 and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance, test or replace the G10 Cooling Fan Motor.
• If the test lamp illuminates
3. Ignition OFF, remove the test lamp and reconnect the KR20P Cooling Fan Medium Speed Relay.
4. Disconnect the harness connector at the G10 Cooling Fan Motor, ignition ON.
5. Command the cooling fan ON at medium speed with a scan tool.
6. Verify a test lamp illuminates between the G10 Cooling Fan Motor medium speed circuit terminal 3 and ground.
• If the test lamp does not illuminate
1. Ignition OFF, remove the test lamp and disconnect the KR20P Cooling Fan Medium Speed Relay, ignition ON.
2. Test for less than 2 ohms in the KR20P Cooling Fan Medium Speed Relay output circuit terminal 87, end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the KR20P Cooling Fan Medium Speed Relay.
• If the test lamp illuminates
7. Test or replace the G10 Cooling Fan Motor.
Component Testing
1. Ignition OFF.
2. Disconnect the appropriate cooling fan relay.
3. Test for 65-105 ohms between terminals 85 and 86.
• If less than 65 ohms or greater than 105 ohms
Replace the appropriate cooling fan relay.
• If between 65-105 ohms
4. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
OR
* 3 and 2
* 3 and 5
* 3 and 1
* 1 and 5
• If less than infinite resistance
Replace the appropriate cooling fan relay.
• If infinite resistance
5. Install a 20 A fused jumper wire between relay terminal 85 and 12 V.
6. Install a jumper wire between relay terminal 86 and ground.
7. Test for less than 2 ohms between terminals 30 and 87.
• If 2 ohms or greater
Replace the appropriate cooling fan relay.
• If less than 2 ohms
8. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Engine Coolant Fan Replacement (2.4L LEA) Engine Coolant Fan ReplacementEngine Coolant Fan Replacement (2.0L LHU) Engine Coolant Fan Replacement
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)