Radiator Fan High Speed 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. 2.

   NO  -Replace the fuse(s) and recheck. If the fuse(s) blow again, repair the short to ground on the No. 3-6 (30A) fuse and the No. 16 (7.5A) fuse circuit.

2. Disconnect and remove the radiator fan relay and the relay circuit board from the under-hood fuse/relay box, then test the radiator fan relay (see POWER RELAY TEST ) and relay circuit board (see FIVE-TERMINAL TYPE ).

   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.

3. Test the radiator fan motor (see FAN MOTOR TEST ).

   Is the motor OK? 

   YES  -Go to step 4.

   NO  -Replace the radiator fan motor (see FAN, FAN MOTOR, AND SHROUD REMOVAL AND INSTALLATION ).

4. Measure the voltage between radiator fan relay 4P socket terminal No. 1 and body ground.
   Fig 1: Measuring Voltage Between Radiator Fan Relay 4P Socket Terminal No. 1 And Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   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.
   Fig 2: Measuring Voltage Between Under-Hood Fuse/Relay Box Connector Terminal B2 And Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there battery voltage? 

   YES  -Turn the ignition switch to LOCK (0), then go to step 7.

   NO  -Repair an 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.
   Fig 3: Checking Continuity Between Radiator Fan Relay 4P Socket Terminal No. 4 And Under-Hood Fuse/Relay Box Connector Terminal B10

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there continuity? 

   YES  -Go to step 8.

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

8. Disconnect the radiator fan motor 2P connector.
9. Check for continuity between radiator fan relay 4P socket terminal No. 2 and radiator fan motor 2P connector terminal No. 2.
   Fig 4: Checking Continuity Between Radiator Fan Relay 4P Socket Terminal No. 2 And Radiator Fan Motor 2P Connector Terminal No. 2

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there continuity? 

   YES  -Go to step 10.

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

10. Check for continuity between radiator fan motor 2P connector terminal No. 1 and under-hood fuse/relay box connector B11.
    Fig 5: Checking Continuity Between Radiator Fan Motor 2P Connector Terminal No. 1 And Under-Hood Fuse/Relay Box Connector B11

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 11.

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

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

    UNDER-HOOD FUSE/RELAY BOX CONNECTOR B (14P) 

    Fig 6: Checking Continuity Between Under-Hood Fuse/Relay Box Connector B1 And Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 12.

    NO  -Repair an 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.

12. Connect the HDS to the DLC (see step 2 on GENERAL TROUBLESHOOTING INFORMATION ).
13. Turn the ignition switch to ON (II).
14. Make sure the HDS communicates with the vehicle and the ECM/PCM. If it does not communicate, troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).
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 radiator fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A5.
    Fig 7: Checking Continuity Between Radiator Fan Relay 4P Socket Terminal No. 3 And ECM/PCM Connector Terminal A5

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 18.

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

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

Fig 8: Checking Continuity Between Under-Hood Fuse/Relay Box Connector D10 And ECM/PCM Connector Terminal A6

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity? 

YES  -Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a know-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then recheck if the symptom/indicate goes away with a know goods ECM/PCM replace the original ECM/PCM (see ECM/PCM REPLACEMENT ).

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