Radiator Fan High Speed Circuit Troubleshooting
Radiator Fan High Speed Circuit Troubleshooting
1.
Fuse check:

Fuse check
?1.
Check the following fuses.
Fuse
Location
No. B12 (30 A)
Under-hood fuse/relay box
No. B31 (7.5 A)
No. C24 (7.5 A)
Under-dash fuse/relay box

Are the fuses OK?

     
YES
     
     
     
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. B12 (30 A), the No. B31 (7.5 A), and the No. C24 (7.5 A) fuse circuits.?
2.
Radiator fan and fan control relays check:

Radiator fan and fan control relays check
?1.
Check the following relays.
Relay
Location
Radiator fan relay
Under-hood fuse/relay box
Fan control relay

Are the relays OK?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Replace the relay(s).?
3.
Open wire check (+B MAIN FAN line):

Open wire check (+B MAIN FAN line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Test point 1
Radiator fan relay 4P socket No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Repair an open in the +B MAIN FAN wire between the radiator fan relay and the No. B12 (30 A) fuse.?
4.
Determine possible failure area (GND line, others):

Determine possible failure area (GND line, others)
?1.
Remove the fan control relay.

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Fan control relay 5P socket No. 1
Terminal B
Fan control relay 5P socket No. 2


?3.
Connect terminals A and B with a jumper wire.
Terminal A
Radiator fan relay 4P socket No. 1
Terminal B
Radiator fan relay 4P socket No. 2


Does the radiator fan run at high speed?

     
YES
     
     
     
Remove the jumper wires, then go to step 9.
     
NO
     
     
     
Remove the jumper wires, then go to step 5.
5.
Radiator fan motor operation check:

Radiator fan motor operation check
?1.
Test the radiator fan motor.

Is the motor OK?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
6.
Open wire check (GND line):

Open wire check (GND line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
 
Fan control relay: disconnected
Test point 1
Fan control relay 5P socket No. 2
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Go to step 7.
     
NO
     
     
     
Repair an open in the GND wire between the fan control relay and ground (G301).?
7.
Open wire check (MAIN FAN MOTOR line):

Open wire check (MAIN FAN MOTOR line)
?1.
Disconnect the following connector.
Radiator fan motor 2P connector

?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
 
Fan control relay: disconnected
 
Radiator fan motor 2P connector: disconnected
Test point 1
Radiator fan relay 4P socket No. 2
Test point 2
Radiator fan motor 2P connector No. 1


Is there continuity?

     
YES
     
     
     
Go to step 8.
     
NO
     
     
     
Repair an open in the MAIN FAN MOTOR wire between the radiator fan relay and the radiator fan motor.?
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.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Fan control relay: disconnected
 
Radiator fan motor 2P connector: disconnected
Test point 1
Fan control relay 5P socket No. 1
Test point 2
Radiator fan motor 2P connector 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.?
     
NO
     
     
     
Repair an open in the FAN HI/LO RLY COM wire between the fan control relay 5P and the radiator fan motor.?
9.
Open wire check (IG2 A/C line):

Open wire check (IG2 A/C line)
?1.
Turn the vehicle to the ON mode.

?2.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle ON mode
Radiator fan relay: disconnected
 
Fan control relay: disconnected
Test point 1
Radiator fan relay 4P socket No. 3
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Go to step 10.
     
NO
     
     
     
Repair an open in the IG2 A/C wire between the radiator fan relay and the No. C24 (7.5 A) fuse.?
10.
Open wire check (FAN LO SIGNAL line):

Open wire check (FAN LO SIGNAL line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Connect the HDS to the DLC.

?3.
Turn the vehicle to the ON mode.

?4.
Make sure the HDS communicates with the vehicle. If it does not communicate, go to the DLC circuit troubleshooting.

?5.
Turn the vehicle to the OFF (LOCK) mode.

?6.
Jump the SCS line with the HDS.
NOTE: This step must be done to protect the PCM from damage.


?7.
Disconnect the following connector.
PCM connector A (51P)

?8.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Fan control relay: disconnected
 
PCM connector A (51P): disconnected
Test point 1
Radiator fan relay 4P socket No. 4
Test point 2
PCM connector A (51P) No. 22


Is there continuity?

     
YES
     
     
     
Go to step 11.
     
NO
     
     
     
Repair an open in the FAN LO SIGNAL wire between the radiator fan relay and the PCM.?
11.
Open wire check (IGP2 SUB line):

Open wire check (IGP2 SUB line)
?1.
Connect the PCM connector.

?2.
Turn the vehicle to the ON mode.

?3.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle ON mode
Radiator fan relay: disconnected
 
Fan control relay: disconnected
Test point 1
Fan control relay 5P socket No. 3
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Go to step 12.
     
NO
     
     
     
Repair an open in the IGP2 SUB wire between the fan control relay and the No. B31 (7.5 A) fuse.?
12.
Open wire check (FAN HI SIGNAL line):

Open wire check (FAN HI SIGNAL line)
?1.
Disconnect the following connector.
PCM connector A (51P)

?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Fan control relay: disconnected
 
PCM connector A (51P): disconnected
Test point 1
Fan control relay 5P socket No. 5
Test point 2
PCM connector A (51P) No. 23


Is there continuity?

     
YES
     
     
     
Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the PCM was substituted, and the symptom/indication goes away, replace the original PCM.?
     
NO
     
     
     
Repair an open in the FAN HI SIGNAL wire between the fan control relay and the PCM.?