Fan 3 Control Circuit Low
The PCM detected a voltage signal below the expected range in the cooling fan 3 relay control circuit. This circuit controls whether the engine's third cooling fan operates, and a low signal prevents the fan from running properly.
What You Might Notice
- Check engine light illuminated
- Engine running hotter than normal
- Cooling fan 3 not operating
- Potential engine overheating during heavy load or idle
- Fan may not engage when temperatures rise
Most Common Causes
- 1
Faulty cooling fan 3 relay
The relay that switches the cooling fan on and off is defective, preventing proper voltage signal to the fan control circuit.
- 2
Blown cooling fan 3 fuse
The dedicated fuse for the cooling fan 3 circuit is open or blown, cutting off power to the relay and control circuit.
- 3
Wiring or connector issues
Corroded, damaged, or loose connections in the cooling fan 3 relay circuit prevent proper voltage signal transmission.
- 4
Faulty PCM or module
The powertrain control module has an internal fault preventing it from properly controlling the cooling fan 3 relay circuit (rare).
How to Diagnose It
- 1
Check Faulty cooling fan 3 relay — The relay that switches the cooling fan on and off is defective, preventing proper voltage signal to the fan control circuit.
- 2
Check Blown cooling fan 3 fuse — The dedicated fuse for the cooling fan 3 circuit is open or blown, cutting off power to the relay and control circuit.
- 3
Check Wiring or connector issues — Corroded, damaged, or loose connections in the cooling fan 3 relay circuit prevent proper voltage signal transmission.
- 4
Check Faulty PCM or module — The powertrain control module has an internal fault preventing it from properly controlling the cooling fan 3 relay circuit (rare).
How to Fix It
- 1
Replace cooling fan 3 relay
Locate the cooling fan 3 relay in the engine bay (typically in a relay box), remove it, and install a new relay of the same part number. Test the cooling fan operation afterward.
- 2
Replace blown cooling fan 3 fuse
Identify the cooling fan 3 fuse in the fuse box using the vehicle's wiring diagram, remove the blown fuse, and install a new one with the same amperage rating.
- 3
Inspect and repair wiring and connectors
Check the cooling fan 3 relay circuit wiring for corrosion, damage, or loose connections. Clean corroded terminals with electrical contact cleaner and ensure all connectors are fully seated and secure.
- 4
Diagnose or replace PCM
Use a diagnostic scanner to confirm the relay and fuse are functioning properly. If all components test good, the PCM may need reprogramming or replacement by a qualified technician.
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