Radiator Fan Circuit Troubleshooting
Radiator Fan Circuit Troubleshooting'04-05 models
NOTE: Before beginning this troubleshooting procedure, refer to the symptom troubleshooting index. Symptom Related Diagnostic Procedures
1. Check the No. 11 (20 A) fuse in the under-hood fuse/relay box, and the No. 30 (7.5 A) fuse in the under-dash fuse/relay box.
Are the fuses OK ?
YES - Go to step 2.
NO - Replace the fuse(s) and recheck.
2. Remove the radiator fan relay from the under-hood fuse/relay box, and test it.
Is the relay OK?
YES - Go to step 3.
NO - Replace the radiator fan 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 terminal No. 1 and No. 2 with a jumper wire.
Does the radiator fan run?
YES - Go to step 5.
NO - Go to step 6.
5. Disconnect the jumper, and turn the ignition switch ON (II). Check for voltage between radiator fan relay 4P socket terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 9.
NO - Repair open in the wire between the underhood fuse/relay box and under-dash fuse/relay box.
6. Disconnect the radiator fan motor 2P connector.
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 - Go to step 8.
NO - Repair open in the wire between the underhood fuse/relay box and radiator fan motor 2P connector terminal No. 2.
8. Check for continuity between radiator fan motor 2P connector terminal No. 1 and body ground.
Is there continuity?
YES - Replace the radiator fan motor.
NO - Repair open in the wire between radiator fan motor 2P connector terminal No. 1 and body ground. If the wire is OK, check for a poor ground at G301.
9. Reinstall the radiator fan relay.
10. Disconnect the radiator fan switch 2P connector.
11. Connect radiator fan switch 2P connector terminal No. 1 and No. 2 with a jumper wire.
Does the radiator fan run?
YES - Replace the radiator fan switch.
NO - Go to step 12.
12. Remove the jumper wire, and measure the voltage between radiator fan switch 2P connector terminal No. 2 and body ground.
Is there battery voltage?
YES - Repair open in the wire between radiator fan switch 2P connector terminal No. 1 and body ground. If the wire is OK, check for a poor ground at G301.
NO - Repair open in the wire between radiator fan switch 2P connector terminal No. 2 and the underhood fuse/relay box.
'06-08 models
NOTE: Before beginning this troubleshooting procedure, refer to the symptom troubleshooting index.
1. Check for the PGM-FI DTCs.
2. Check the No. 11 (20 A) fuse in the under-hood fuse/relay box, and the No. 30 (7.5 A) fuse in the under-dash fuse/relay box.
Are the fuses OK ?
YES - Go to step 3.
NO - Replace the fuse(s) and recheck.
3. Remove the radiator fan relay from the under-hood fuse/relay box, and test it.
Is the relay OK?
YES - Go to step 4.
NO - Replace the radiator fan relay.
4. Measure the voltage between radiator fan relay 4P socket terminal No. 2 and body ground.
Is there battery voltage?
YES - Go to step 5.
NO - Replace the under-hood fuse/relay box.
5. Connect radiator fan relay 4P socket terminal No. 1 and No. 2 with a jumper wire.
Does the radiator fan run?
YES - Go to step 6.
NO - Go to step 7.
6. Disconnect the jumper, and turn the ignition switch ON (II). Check for 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 underhood fuse/relay box and under-dash fuse/relay box.
7. Disconnect the radiator fan motor 2P connector.
8. 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 - Go to step 9.
NO - Repair open in the wire between the underhood fuse/relay box and radiator fan motor 2P connector terminal No. 2.
9. Check for continuity between radiator fan motor 2P connector terminal No. 1 and body ground.
Is there continuity?
YES - Replace the radiator fan motor.
NO - Repair open in the wire between radiator fan motor 2P connector terminal No. 1 and body ground. If the wire is OK, check for a poor ground at G301.
10. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC).
11. Turn the ignition switch ON (II).
12. '07-08 models: Make sure the HDS communicates with the vehicle and the engine control module (ECM)/powertrain control module (PCM). If it doesn't communicate, troubleshoot the DLC circuit.
13. Jump the SCS line with the HDS, then turn the ignition switch OFF.
NOTE: This step must be done to protect the ECM/PCM from damage.
14. Disconnect ECM/PCM connector E (31P).
15. Disconnect under-hood fuse/relay box connector E (16P).
16. Check for continuity between ECM/PCM connector terminal E12 and under-hood fuse/relay box terminal E14.
Is there continuity?
YES - Circuit is OK. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. if the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
NO - Repair open in the wire between the underhood fuse/relay box and the ECM/PCM.