Radiator Fan High Speed Circuit Troubleshooting

Engine

Radiator Fan High Speed Circuit Troubleshooting

Radiator Fan High Speed Circuit Troubleshooting

1. Fuse check:

Fuse check
-1. Check the following fuses.










Are the fuses OK?
-YES- The fuses are OK. Reinstall the fuses, then go to step 2.
-NO- Replace the fuse(s), and recheck. If the fuse(s) blows again, repair the short to ground on the No. A2-11 (20 A) fuse and No. B22 (7.5 A) fuse circuit.

2. Relay check:

Relay check
-1. Remove the radiator fan relay and the fan control relay from the under-hood fuse/relay box, and test them Testing and Inspection.

Are the relays OK?
-YES- The relays are OK. Go to step 3.
-NO- Replace the relay(s).

3. Determine possible failure area (under-hood fuse/relay box, fan control circuit):

Determine possible failure area (under-hood fuse/relay box, fan control circuit)
-1. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 4.
-NO- Replace the under-hood fuse/relay box.

4. Determine possible failure area (GND line, other lines):

Determine possible failure area (GND line, other lines)
-1. Connect terminals A and B with a jumper wire.









-2. Connect terminals A and B with a jumper wire.









Does the radiator fan run at high speed?
-YES- Go to step 9.
-NO- Go to step 5.

5. Open wire check (GND line):

Open wire check (GND line)
-1. Disconnect the jumper wires.

-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The GND wire is OK. Go to step 6.
-NO- Repair an open in the GND wire between the fan control relay 5P socket and the ground (G301).

6. Radiator fan motor operation check:

Radiator fan motor operation check
-1. Test the radiator fan motor Testing and Inspection.

Is the motor OK?
-YES- The radiator fan motor is OK. Go to step 7.
-NO- Replace the radiator fan motor; except K24Z7 engine Service and Repair, K24Z7 engine Service and Repair.

7. Open wire check (MAIN_FAN_MOTOR line):

Open wire check (MAIN_FAN_MOTOR line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The MAIN_FAN_MOTOR wire is OK. Go to step 8.
-NO- Repair an open in the MAIN_FAN_MOTOR wire between the radiator fan relay 4P socket and the radiator fan motor 2P connector.

8. Open wire check (FAN_HI/LO_RLY_COM line):

Open wire check (FAN_HI/LO_RLY_COM line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The FAN_HI/LO_RLY_COM wire is OK. Check for poor connections or loose terminals at the under-hood fuse/relay box, the radiator fan motor, and ground G301, then go to step 1.
-NO- Repair an open in the FAN_HI/LO_RLY_COM wire between the fan control relay 5P socket and the radiator fan motor 2P connector.

9. Open wire check (MAIN_FAN_DIODE- line) 1:

Open wire check (MAIN_FAN_DIODE- line) 1
-1. Disconnect the jumper wires.

-2. Turn the ignition switch to ON (II).

-3. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- The MAIN_FAN_DIODE- wire is OK. Go to step 10.
-NO- Repair an open in the MAIN_FAN_DIODE- wire between the radiator fan relay 4P socket and the under-dash fuse/relay box.

10. Open wire check (RFC_RLY_CL- line):

Open wire check (RFC_RLY_CL- line)
-1. Turn the ignition switch to LOCK (0).

-2. Connect the HDS to the DLC; except K24Z7 engine How To Troubleshoot The Fuel And Emissions Systems, K24Z7 engine How To Troubleshoot The Fuel And Emissions Systems.

-3. Turn the ignition switch to ON (II).

-4. Make sure the HDS communicates with the vehicle and the ECM/PCM. If it does not communicate, troubleshoot the DLC circuit; except K24Z7 engine Testing and Inspection, K24Z7 engine Testing and Inspection.

-5. 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.

-6. Disconnect the following connector.





-7. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The RFC_RLY_CL- wire is OK. Go to step 11.
-NO- Repair an open in the RFC_RLY_CL- wire between the radiator fan relay 4P socket and the ECM/PCM.

11. Open wire check (MAIN_FAN_DIODE- line) 2:

Open wire check (MAIN_FAN_DIODE- line) 2
-1. Turn the ignition switch to ON (II).

-2. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- The MAIN_FAN_DIODE- wire is OK. Go to step 12.
-NO- Repair an open in the MAIN_FAN_DIODE- wire between the fan control relay 5P socket and the under-dash fuse/relay box.

12. Open wire check (FAN_HI_SIGNAL line):

Open wire check (FAN_HI_SIGNAL line)
-1. Turn the ignition switch to LOCK (0).

-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The FAN_HI_SIGNAL wire is OK. Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM; except K24Z7 engine , K24Z7 engine Service and Repair, then recheck. If the ECM/PCM was substituted, and the symptom/indication goes away, replace the original ECM/PCM; except K24Z7 engine , K24Z7 engine Service and Repair.
-NO- Repair an open in the FAN_HI_SIGNAL wire between the fan control relay 5P socket and the ECM/PCM.