Radiator Fan High Speed Circuit Troubleshooting

Radiator Fan High Speed Circuit Troubleshooting

1. Check the No. B29 (30 A) fuse, the No. B10 (15 A) fuse, the No. B30 (30 A) fuse, and the No. B28 (7.5 A) fuse in the under-hood fuse/relay box, and the No. C26 (7.5 A) fuse in the driver's under-dash fuse/relay box.

Are the fuses OK?

YES -

Reinstall the fuses, 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. B29 (30A) fuse, the No. B10 (15A) fuse, the No. B30 (30A) fuse, the No. B28 (7.5A) fuse, and the No. C26 (7.5A) fuse circuit.

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

Are relays OK?

YES -

Go to step 3.

NO -

Replace the relay(s).

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 Under-Hood Fuse/Relay Box Removal and Installation.

4. 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 9.

NO -

Remove the jumper wire, then go to step 5.

5. Test the radiator fan motor Testing and Inspection.

Is the fan motor OK?

YES -

Go to step 6.

NO -

Replace the radiator fan motor Radiator And A/C Condenser Fan, Motor, And Shroud Removal And Installation.

6. Disconnect the radiator fan motor 2P connector.

7. Check for continuity between radiator fan relay 4P socket terminal No. 2 and radiator fan motor 2P connector terminal No. 1.





Is there continuity?

YES -

Go to step 8.

NO -

Repair an open in the wire between radiator fan relay 4P socket terminal No. 2 and radiator fan motor 2P connector terminal No. 1.

8. Check for continuity between radiator fan motor 2P connector terminal No. 2 and body ground.





Is there continuity?

YES -

Check for poor connections or loose terminals at the radiator fan motor and body ground G201.

NO -

Repair an open in the wire between radiator fan motor 2P connector terminal No. 2 and body ground.

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

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





Is there battery voltage?

YES -

Go to step 11.

NO -

Repair an open in the wire between driver's under-dash fuse/relay box connector terminal F17 and fan control relay 5P socket terminal No.5.

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





Is there battery voltage?

YES -

Go to step 12.

NO -

Check the PGM-FI main relay 1 Testing and Inspection. If the relay is OK, replace the under-hood fuse/relay box Under-Hood Fuse/Relay Box Removal and Installation.

12. Connect the HDS to the DLC.

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

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

15. 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.

16. Disconnect PCM connector A (49P).

17. Check for continuity between PCM connector terminal A5 and radiator fan relay 4P socket terminal No. 4.





Is there continuity?

YES -

Go to step 18.

NO -

Repair an open the wire between radiator fan relay 4P socket terminal No. 4 and PCM connector terminal A5.

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





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 Service and Repair.

NO -

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