Fan 2 Control Circuit High
The PCM detected an abnormally high voltage signal in the Cooling Fan 2 relay control circuit, indicating the relay is not functioning properly or the circuit has a short to power. This prevents the cooling fan from operating, creating an immediate risk of engine overheating.
What You Might Notice
- Check engine light illuminated
- Engine overheating or running hot
- Cooling fan 2 not operating
- Temperature gauge in red zone
- Potential steam from radiator
Most Common Causes
- 1
Faulty Cooling Fan 2 Relay
The relay contacts are stuck open or the relay coil is damaged, preventing the relay from closing and supplying power to the cooling fan motor.
- 2
Blown Cooling Fan 2 Fuse
A blown fuse in the cooling fan 2 circuit cuts power to the relay, causing a high voltage signal at the relay control pin.
- 3
Wiring Harness Short to Power
Damaged or pinched wiring in the cooling fan relay control circuit may be shorted directly to battery voltage instead of ground.
- 4
Faulty PCM or Module
The powertrain control module may have internal damage preventing it from properly grounding the relay control circuit (rare but possible).
How to Diagnose It
- 1
Check Faulty Cooling Fan 2 Relay — The relay contacts are stuck open or the relay coil is damaged, preventing the relay from closing and supplying power to the cooling fan motor.
- 2
Check Blown Cooling Fan 2 Fuse — A blown fuse in the cooling fan 2 circuit cuts power to the relay, causing a high voltage signal at the relay control pin.
- 3
Check Wiring Harness Short to Power — Damaged or pinched wiring in the cooling fan relay control circuit may be shorted directly to battery voltage instead of ground.
- 4
Check Faulty PCM or Module — The powertrain control module may have internal damage preventing it from properly grounding the relay control circuit (rare but possible).
How to Fix It
- 1
Replace Cooling Fan 2 Relay
Locate the cooling fan relay in the engine bay fuse/relay box, test it with a multimeter, and replace with an OEM or equivalent relay if it fails continuity or resistance tests.
- 2
Replace Blown Cooling Fan Fuse
Check the fuse box for the cooling fan 2 fuse, verify it is blown, and replace with the correct amperage fuse. If it blows again immediately, there is a short in the circuit.
- 3
Inspect and Repair Wiring Harness
Visually inspect the cooling fan relay control wiring for damage, cuts, or pinching. Test continuity between the relay control pin and the PCM connector. Repair or replace damaged wiring sections.
- 4
Replace PCM if Necessary
If relay and wiring test good, the PCM may need replacement. This is rare and should only be done after all other components are confirmed working properly.
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