Diagnostic Trouble Code Tests and Associated Procedures: 564

Service code 564 indicates a Low Speed Electro-Drive Fan (EDF) circuit failure.

1. Check EDF signal for short to ground.

Note: For fan always on with a code 564, go to step 3.

^ 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, and loose wires. Service as necessary.

^ Install a breakout box, leaving the processor disconnected.

^ Measure resistance between test pin 13 and test pin 40 at the breakout box.

^ Is the resistance greater than 10,000 ohms?

YES -- Go to step 2.

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

2. Check fan running mode.

^ Key off, breakout box installed, processor disconnected.

^ Connect the IRCM.

^ Key on, engine off.

^ Does the fan run?

YES -- Replace the processor, and retest.

NO -- Replace the IRCM, and retest.

3. Check 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, and 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 4.

NO -- Service open in the EDF circuit, and retest.

4. Check EDF circuit for shorts 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 terminal.

^ Is each resistance greater than 10,000 ohms.

YES -- Go to step 5.

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

5. Check EDF circuit for shorts to ground.

^ Key off, breakout box installed, processor disconnected.

^ Reconnect the IRCM.

^ 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.