Fan 1 Control Circuit Low
The engine control module detected a low voltage condition in the cooling fan 1 relay control circuit. This means the PCM cannot properly command the cooling fan to operate, preventing the radiator from cooling the engine effectively.
What You Might Notice
- Check engine light illuminated
- Engine running hotter than normal
- Cooling fan not running when engine is warm
- Potential engine overheating under load or traffic
- Possible engine shutdown due to overtemp protection
Most Common Causes
- 1
Faulty cooling fan relay 1
The relay that controls power to the cooling fan motor has failed or has internal contact issues, preventing it from completing the circuit.
- 2
Blown cooling fan fuse
The fuse protecting the cooling fan circuit has opened, cutting power to the relay coil or fan motor circuit.
- 3
Wiring or connector issues
Corroded, loose, or damaged wiring and connectors in the cooling fan relay circuit can cause low voltage conditions.
- 4
Faulty PCM
Rarely, the powertrain control module itself may fail in its ability to output the proper control signal to the relay.
How to Diagnose It
- 1
Check Faulty cooling fan relay 1 — The relay that controls power to the cooling fan motor has failed or has internal contact issues, preventing it from completing the circuit.
- 2
Check Blown cooling fan fuse — The fuse protecting the cooling fan circuit has opened, cutting power to the relay coil or fan motor circuit.
- 3
Check Wiring or connector issues — Corroded, loose, or damaged wiring and connectors in the cooling fan relay circuit can cause low voltage conditions.
- 4
Check Faulty PCM — Rarely, the powertrain control module itself may fail in its ability to output the proper control signal to the relay.
How to Fix It
- 1
Replace cooling fan relay 1
Locate the cooling fan relay in the engine bay fuse/relay box using the underhood diagram, and swap in a new relay of the same part number.
- 2
Replace blown cooling fan fuse
Find the cooling fan fuse in the fuse box, remove the blown fuse, and install a new fuse of the correct amperage rating.
- 3
Inspect and repair wiring and connectors
Examine all connectors and wiring harnesses in the cooling fan relay circuit for corrosion, loose terminals, or damage. Clean or replace as needed.
- 4
Reprogram or replace PCM
If basic checks pass, have the PCM reprogrammed with the latest software or replaced by a professional technician.
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