P0695Fan 3 Control Circuit Low
The control circuit for cooling fan 3 is reading lower voltage than expected, usually from a short to ground in the third fan's relay or wiring.
Definition
Some vehicles use a third cooling fan or a third relay stage (for series/parallel speed control), and the PCM monitors that control line like the others. P0695 sets when the fan 3 control circuit voltage is below the expected value for the commanded state, indicating a short to ground or excessive current draw. The most common consequence is losing the highest fan speed, so the engine may overheat at idle with A/C on or during towing, and the MIL illuminates.
Common causes
- Fan 3 control wiring shorted to ground
- Shorted relay coil in the fan 3 or high-speed relay
- Corroded connector at the relay box or fan assembly
- Fan motor pulling excessive current through the high-speed circuit
- Faulty PCM driver
Common misdiagnoses
- Fan motors replaced when a relay in the series/parallel arrangement failed
- Radiator or water pump blamed for marginal cooling caused by the missing high fan speed
- PCM replaced without isolating the shorted circuit
Troubleshooting steps
1.Identify the fan arrangement from the wiring diagram
On series/parallel systems, relay 3 often creates high speed — knowing the topology tells you which speeds should be missing.
2.Command each fan stage with a scan tool
Step through low/medium/high commands and confirm which stage fails to respond.
3.Measure the fan 3 control-circuit voltage
A line pinned near 0 V in all commanded states points to a short to ground between the PCM and relay.
4.Swap or bench-test the relay
Compare coil resistance to the other fan relays and substitute a known-good relay.
5.Isolate the harness short
With the relay and PCM disconnected, check the control wire for continuity to ground and repair chafed sections.