KF44 - Check LFC and HFC Relay Operation

- Key "OFF".

- Cooling fan(s) disconnected.

- Reconnect Low Fan Control (LFC) and High Fan Control (HFC) relays.

- Enter Output State Diagnostic Test Mode. Output State Diagnostic Test Mode

- Outputs "OFF".

- Check LFC relay operation:

- Depress throttle to Wide Open Throttle (WOT), wait until Malfunction Indicator Light (MIL) flashes once (about 10 seconds). Release throttle. The LFC output is now "ON".

- Measure voltage between the Power-to-Fan circuit at the cooling fan vehicle harness connector and the battery negative post.

- Voltage should be greater than 10.0 volts.

- Depress throttle and release to cycle outputs "OFF".

- Check HFC relay operation:

- Depress throttle to WOT, wait until MIL flashes once, then twice (about 15 seconds). Release throttle. The LFC output is now "ON".

- Measure voltage between the Power-to-Fan circuit at the cooling fan vehicle harness connector and the battery negative post.

- Voltage should be greater than 10.5 volts.

- Do the LFC and HFC relays operate correctly?

Yes -- Key "OFF". Replace cooling fan(s). Reconnect all components. Re-evaluate symptom.

No -- Key "OFF". Replace inoperative LFC or HFC relay. Reconnect all components. Re-evaluate symptom.