Radiator Fan High Speed Circuit Troubleshooting

Radiator Fan High Speed Circuit Troubleshooting

1. Check the No. 7 (30 A) fuse in the under-hood fuse/relay box and the No. 36 (10 A) fuse in the under-dash fuse/relay box.

Are the fuse(s) OK?

YES -

Reinstall the fuse(s), then go to step 2.

NO -

Replace the fuse(s) and recheck. If the fuse(s) blow again, repair the short to ground on the No. 7 (30A) fuse and the No. 36 (10A) fuse circuit.

2. Remove the radiator fan relay and the fan control relay from the under-hood fuse/relay box, and test it Testing and Inspection.

Are the relays OK?

YES -

Go to step 3.

NO -

Replace the radiator fan relay and/or fan control relay.

3. Measure the voltage between radiator fan relay 4P socket terminal No. 1 and body ground.





Is there battery voltage?

YES -

Go to step 4.

NO -

Replace the under-hood fuse/relay box.

4. Connect fan control relay 5P socket terminals No. 1 and No. 2 with a jumper wire.






5. Connect radiator fan relay 4P socket terminals No. 1 and No. 2 with a jumper wire.





Does the radiator fan run at high speed?

YES -

Remove the jumper wire, then go to step 10.

NO -

Remove the jumper wire, then go to step 6.

6. Test the radiator fan motor Testing and Inspection.

Is the fan motor OK?

YES -

Go to step 7.

NO -

Replace the radiator fan motor Service and Repair.

7. Check for continuity between fan control relay 5P socket terminal No. 2 and body ground.





Is there continuity?

YES -

Go to step 8.

NO -

Repair an open in the wire between fan control relay 5P socket terminal No. 2 and body ground.

8. Check for continuity between radiator fan relay 4P socket terminal No. 2 and radiator fan motor 2P connector terminal No. 2.





Is there continuity?

YES -

Go to step 9.

NO -

Repair an open in the wire between radiator fan relay 4P socket terminal No. 2 and radiator fan motor 2P connector terminal No. 2.

9. Check for continuity between fan control relay 5P socket terminal No. 1 and radiator fan motor 2P connector terminal No. 1.





Is there continuity?

YES -

Go to step 10.

NO -

Repair an open in the wire between fan control relay 5P socket terminal No. 1 and radiator fan motor 2P connector terminal No. 1.

10. Turn the ignition switch to ON (II).

11. Measure the voltage between fan control relay 5P socket terminal No. 5 and body ground.





Is there battery voltage?

YES -

Go to step 12.

NO -

Repair an open in the wire between the under dash fuse/relay box and the under hood fuse/relay box.

12. Turn the ignition switch to LOCK (0).

13. Connect the HDS to the DLC.

14. Turn the ignition switch to ON (II).

15. Make sure the HDS communicates with the vehicle and the PCM. If it does not communicate, troubleshoot the DLC circuit Testing and Inspection.

16. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0).

NOTE: This step must be done to protect the PCM from damage.

17. Disconnect PCM connector A (49P).

18. Check for continuity between fan control relay 5P socket terminal No. 3 and PCM connector terminal A5.





Is there continuity?

YES -

Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM PCM Replacement (Except FFV Model).

NO -

Repair an open in the wire between fan control relay 5P socket terminal No. 3 and PCM connector terminal A5.