High Speed Fan Always on

1. High Speed Cooling Fan (HEDF) always on, check for short to power.

^ With the key off, disconnect the Integrated Control Relay Module (IRCM) and the cooling fan.

^ Measure resistance between pin 6 and pins 8, 13, and 24 at the IRCM vehicle harness.

^ Are all resistance readings greater than 10,000 ohms?

YES -- Reconnect the IRCM and cooling fan, go to step 2.

NO -- Service the HEDF circuit for shorts to power.

2. Check processor for short to ground.

^ Key off, IRCM and cooling fan connected.

^ Disconnect the processor 60 pin connector. Inspect for damaged or pushed out pins, corrosion, and loose wires. Service as necessary.

^ Key on, engine off.

^ Is the high speed cooling fan off?

YES -- Replace the processor.

NO -- Go to step 3.

3. Check HEDF circuit for short to ground.

^ With the key off, disconnect the IRCM.

^ Install a breakout box, leaving the processor disconnected.

^ Measure resistance between test pin 31 and test pin 40 (or 60) at the breakout box.

^ Is the resistance greater than 10,000 ohms?

YES -- Replace the IRCM, and retest.

NO -- Service the HEDF circuit between the IRCM and the processor for a short to ground, and retest.