Radiator Fan Circuit Troubleshooting

Radiator Fan Circuit Troubleshooting

1. Check the No. 3-6 (30 A) fuse in the under-hood fuse/relay box and No. 16 (7.5 A) fuse in the driver's under-dash fuse/relay box.

Are the fuses OK?
YES - 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, driver's under-dash fuse/relay box connector terminal F26 and under-hood fuse/relay box connector terminal B2.


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

Are the radiator fan relay and the relay circuit board OK?
YES - Go to step 3.

NO - Replace the radiator fan relay and/or the relay circuit board, then retest.


3. Test the radiator fan motor. Testing and Inspection

Is the motor OK?
YES - Go to step 4.

NO - Replace the radiator fan motor. Service and Repair


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

Is there battery voltage?
YES - Go to step 5.

NO - Replace the under-hood fuse/relay box.






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

6. Measure the voltage between under-hood fuse/relay box connector terminal B2 and body ground.

Is there battery voltage?
YES - Turn the ignition switch to LOCK (0), then go to step 7.

NO - Repair open in the wire between driver's under-dash fuse/relay box connector terminal F26 and under-hood fuse/relay box connector terminal B2.






7. Check for continuity between radiator fan relay 4P socket terminal No. 4 and under-hood fuse/relay box connector terminal B10.

Is there continuity?
YES - Go to step 8.

NO - Replace the under-hood fuse/relay box.






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

9. Disconnect the radiator fan motor 2P connector.

10. 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 11.

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






11. Check for continuity between radiator fan motor 2P connector terminal No. 1 and under-hood fuse/relay box connector B11.

Is there continuity?
YES - Go to step 12.

NO - Repair open in the wire between radiator fan motor 2P connector terminal No. 1 and under-hood fuse/relay box connector B11.






12. Check for continuity between under-hood fuse/relay box connector B1 and body ground.

Is there continuity?
YES - Go to step 13.

NO - Repair open in the wire between under-hood fuse/relay box connector B1 and body ground. If the wire is OK, check for a poor ground at G301.






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

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

15. Make sure the HDS communicates with the vehicle and the engine control module (ECM)/powertrain control module (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 ECM/PCM from damage.

17. Disconnect ECM/PCM connector A (49P)

18. Check for continuity between radiator fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5.

Is there continuity?
YES - Go to step 19.

NO - Repair open in the wire between the under-hood fuse/relay box 4P socket terminal No. 3 and ECM/PCM connector terminal A5.






19. Check for continuity between under-hood fuse/relay box connector D10 and ECM/PCM connector terminal A6.

Is there continuity?
YES - Update the ECM/PCM if it does not have the latest software, ECM/PCM Update or substitute a known-good ECM/PCM, Initial Inspection and Diagnostic Overview then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM. ECM/PCM Replacement (A/T)

NO - Repair open in the wire between the under-hood fuse/relay box connector D10 and ECM/PCM connector terminal A6.