Low Speed Fan Always on

1. Check Low Electro-Drive Fan (EDF) circuit continuity.

^ With the key off, disconnect the Integrated Relay Control Module (IRCM) and the processor 60 pin connector. Inspect for damaged or pushed out pins, corrosion, or loose wires. Service as necessary.

^ Install a breakout box, leaving the processor disconnected.

^ Measure resistance between test pin 13 at the breakout box and pin 14 at the IRCM vehicle harness connector.

^ Is the resistance less than 5.0 ohms?

YES -- Go to step 2.

NO -- Service open in the Low Speed Electro-Drive (EDF) circuit, and retest.

2. Check the EDF circuit for short to power.

^ Key off, breakout box installed, processor and IRCM disconnected.


^ Measure resistance between test pin 13 and test pin 37 and between test pin 13 and battery positive post.

^ Is each resistance greater than 10,000 ohms?

YES -- Go to step 3.

NO -- Service short to power in the EDF circuit, and retest.

3. EDF circuit fault isolation.

^ With the key off and the breakout box still installed, reconnect the IRCM, leaving the processor disconnected.

^ Key on, engine off.

^ Jumper test pin 13 to test pin 40 or 60 at the breakout box.

^ Does the fan continue to run?

YES -- Replace the IRCM, and retest.

NO -- Replace the processor and retest.