Radiator Fan High Speed Circuit Troubleshooting

Radiator Fan High Speed Circuit Troubleshooting

1. Check the No. 11 (30 A) fuse in the under-hood fuse/relay box, and the No. 23 (7.5 A) fuse and the No. 30 (10 A) fuse in the driver's 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 continues to blow, locate and repair the short in the circuit between the under-hood fuse/relay box and the radiator fan motor, and driver's under-dash fuse/relay box and the under-hood fuse/relay box.�

2. Remove the radiator fan relay from the under-hood fuse/relay box, and remove the fan control relay from the auxiliary under-hood relay box, and test it. Power Relay Test.

Are the relay(s) 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. 2 and body ground.





Is there battery voltage?

YES -

Go to step 4.

NO -

Replace the under-hood fuse/relay box.�

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 -

Go to step 8.

NO -

Go to step 5.

5. Disconnect the radiator fan motor 2P connector, then test the fan motor Testing and Inspection.

Is the fan motor OK?

YES -

Go to step 6.

NO -

Replace the radiator fan motor, and retest.

6. Check for continuity between radiator fan motor 2P connector terminal No. 1 and body ground.





Is there continuity?

YES -

Go to step 7.

NO -

Repair open in the wire between radiator fan motor 2P connector terminal No. 1 and body ground.�

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





Is there continuity?

YES -

Check for poor connections or loose terminals at the under-hood fuse/relay box and the radiator fan motor, the radiator fan motor and body ground (G301).�

NO -

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

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

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





Is there battery voltage?

YES -

Go to step 10.

NO -

Repair open in the wire between the driver's under-dash fuse/relay box and the under-hood fuse/relay box.�

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

11. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) Initial Inspection and Diagnostic Overview.

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

13. Make sure the HDS communicates with the vehicle and the powertrain control module (PCM). If it does not communicate, troubleshoot the DLC circuit Testing and Inspection.

14. 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.

15. Disconnect PCM connector A (49P).

16. Check for continuity between radiator fan relay 4P socket terminal No. 4 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 Initial Inspection and Diagnostic Overview, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM Service and Repair.�

NO -

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