Cooling Fan Control Fault Diagnostics
SPECIAL TOOLS NEEDED:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
Connect the GPEC Adaptor to the PCM harness connector when probing the PCM connectors.
(special tool #10436, Adapter, GPEC Diagnostic)
TECH TIPS:
- The radiator fans do not share a Fused B+ power supply. There are two independent Fused B+ power supplies, one for each fan. Each supply circuit is protected by a fuse. If a radiator fan is inoperative at both low and high speeds, inspect the fuse for the fan in the PDC. If only low speed or high speed are inoperative, the fuse is not the cause of the issue.
- The (N112) Low speed relay control operates both Radiator Fan Relays 1 and 2 in the PDC. One failed relay or open power supply to the relay coil will not set the control circuit fault. Only one relay operating properly is needed for the PCM to sense activation. For the P0480 fault to set it requires an open/shorted control circuit or two faulty relays or power supplies.
SCAN TOOL ACTUATOR TIPS:
- Rad/Cond Cooling Fan Relay #1 Control State actuator turns on the radiator fan low relay control driver. This is the control circuit for both low speed fan relays in the PDC. Both fans should run at low speed when selected.
- Rad/Cond Cooling Fan Relay #2 Control State actuator turns on the radiator fan 1 high relay control driver. This should cause radiator fan 1 (left fan) to run at high speed.
- Radiator Fan 2 high speed relay does not have an actuator. To test Fan 2 high speed requires removing the fan 2 high relay and adding a fused jumper between terminals 30 and 87 in the Radiator Fan 2 High Relay connector while actuating the Rad/Cond Cooling Fan Relay #1 Control State with the scan tool. The other option is to run the A/C system on max A/C and bring the vehicle to operating temperature to allow the fans to naturally operate at high speed.
DETERMINE THE SYMPTOMS AND FAULT CODES THAT ARE PRESENT: Using the scan tool, operate the radiator fans to determine which fan is not operating at which speed. Note: If there is an issue with a control circuit or power supply circuit a corresponding fault may also set in the PCM when running the actuator tests.
IMPORTANT: The left fan and related relays is Radiator Cooling Fan 1. The right fan and related relays is Radiator Cooling Fan 2. The fan positions are determined by sitting in the drivers seat looking forward.
- Use the symptom and faults to reference the correct diagnostic information below.