Diesel Data: Automotive Repair

Radiator and A/C Condenser Fan Common Circuit Troubleshooting

Radiator and A/C Condenser Fan Common Circuit Troubleshooting

NOTE:
- Do not use this troubleshooting procedure if only one fan is inoperative, or if the A/C compressor is inoperative. Refer to the symptom troubleshooting index. Symptom Related Diagnostic Procedures
- Before performing symptom troubleshooting, check for powertrain DTCs.

1. Check the No. 57 (20 A) and No. 58 (20 A) fuses in the main under-hood fuse/relay box, and the No. 20 (7.5 A) fuse in the under-dash fuse/relay box.

Are the fuses OK?

YES - Go to step 2.

NO - Replace the fuse(s), and recheck.

2. Remove the A/C condenser fan relay from the main under-hood fuse/relay box.
3. Turn the ignition switch ON (II).




4. Measure the voltage between the No. 3 terminal of the A/C condenser fan relay 4P socket and body ground.

Is there battery voltage?

YES - Go to step 5.

NO - Repair open in the wire between the No. 20 (7.5 A) fuse in the under-dash fuse/relay box and the radiator fan relay, and the A/C condenser fan relay.

5. Turn the ignition switch OFF.
6. Reinstall the A/C condenser fan relay.
7. Make sure the A/C switch is OFF.
8. Turn the ignition switch ON (II).




9. Using a backprobe set, measure the voltage between the No. 20 terminal of ECM connector A (32P) and body ground with the ECM connectors connected ('00-05 models) or between the No. 12 terminal of ECM connector E (31P) and body ground with the ECM connectors connected ('06 model).

Is there battery voltage?

YES - Check for loose wires or poor connections at ECM connector A (32P) ('00-05 models), or ECM connector E (31P) ('06 model). If the connections are good, substitute a known-good ECM, and recheck. If the symptom/indication goes away, replace the original ECM.

NO - Repair open in the wire between the radiator fan relay, the A/C condenser fan relay and the ECM.