X42 - Jumper High Fan Control (HFC) Signal to Ground

- Key "OFF".

- Inspect Powertrain Control Module (PCM) for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

- Install breakout box, leave PCM disconnected.

- Constant Control Relay Module (CCRM) connected.

- Key "ON", engine "OFF".

- Jumper test pin 31 to test pin 40 at the breakout box.

- Does fan speed change from low to high?

Yes -- Go to X44. X44 - Check ECT Sensor

No -- Replace CCRM. Remove breakout box. Reconnect PCM. Re-evaluate symptom.