Radiator Fan High Speed Circuit Troubleshooting

Radiator Fan High Speed Circuit Troubleshooting

1. Check the No. 3-6 (30 A) fuse, the No. 14 (15 A) fuse, and the No. 21 (7.5 A) fuse in the under-hood fuse/relay box, and the No. 16 (7.5 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 relay circuit board, the under-hood fuse/relay box and the radiator fan motor, the driver's under-dash fuse/relay box connector terminal F26 and the under-hood fuse/relay box connector terminal B10.


2. Disconnect and remove the relay circuit board from the under-hood fuse/relay box, and test it. Testing and Inspection

Is the relay circuit board OK?
YES - Go to step 3.

NO - Replace the relay circuit board.


3. Measure the voltage between under-hood fuse/relay box connector terminal C1 and body ground.

Is there battery voltage?
YES - Go to step 4.

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






4. Connect under-hood fuse/relay box connector terminals C1 and B2 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 under-hood fuse/relay box connector terminal B2 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 under-hood fuse/relay box connector terminal B2 and radiator fan motor 2P connector terminal No. 2.






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

9. Measure the voltage between under-hood fuse/relay box connector terminal B10 and body ground.

Is there battery voltage?
YES - Go to step 10.

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 B10.






10. Measure the voltage between under-hood fuse/relay box connector terminal B7 and body ground.

Is there battery voltage?
YES - Go to step 11.

NO - Check the PGM-FI subrelay. If the relay is OK, replace the under-hood fuse/relay box.






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

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

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

14. 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

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 ECM/PCM from damage.

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

17. Check for continuity between ECM/PCM connector terminal A5 and under-hood fuse/relay box connector terminal B11.

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. Service and Repair

NO - Repair open the wire between under-hood fuse/relay box connector B11 and ECM/PCM connector terminal A5.