P0696Fan 3 Control Circuit High
The control circuit for cooling fan 3 is reading higher voltage than expected, typically from an open circuit, failed relay, or short to battery voltage.
Definition
On systems with three fan relays or a third fan stage, the PCM expects the fan 3 control line to pull low when commanded on. P0696 sets when the circuit stays high — an open control wire, an open relay coil, or a short to power. This usually eliminates the highest cooling stage, so overheating shows up under peak demand such as idling with A/C on, towing, or hot-weather stop-and-go, accompanied by an illuminated MIL.
Common causes
- Open in the fan 3 control wiring or connector terminal
- Open relay coil in the fan 3/high-speed relay
- Control wire shorted to battery voltage
- Heat-damaged relay socket in the underhood fuse box
- Faulty PCM driver
Common misdiagnoses
- Fan motors replaced when the high-speed relay circuit is open
- Thermostat replaced for heat-soak complaints caused by the missing fan stage
- A/C condenser or refrigerant charge blamed for pressure complaints from lost airflow
Troubleshooting steps
1.Command the fan 3 stage with a scan tool
Verify the highest fan stage fails to engage while lower stages work.
2.Check control-wire continuity
Measure from the PCM to the relay socket for under about 1 ohm; an open indicates a broken wire or terminal.
3.Test the relay
Measure the coil against a sibling fan relay and swap in a known-good unit to confirm.
4.Check for short to voltage
Battery voltage on the control line with the relay removed and the output commanded on means the harness is contacting a power feed.
5.Prove the fan motor directly
Jumper power and ground to the fan's high-speed circuit to confirm the motor before replacing control components.