Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting
Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting
NOTE:
Do not use this troubleshooting procedure if the A/C compressor is inoperative. Refer to the symptom troubleshooting index.
If the A/C system is inoperable, the radiator and A/C condenser fans are controlled based only on engine coolant temperature.
Before doing symptom troubleshooting, check for PGM-FI DTCs.
1.
Fuse check:

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

Is the fuse OK?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Replace the fuse, and recheck. If the fuse blows again, repair a short in the No. B12 (30 A) fuse circuit.?
2.
PGM-FI system parameter check:

PGM-FI system parameter check
?1.
Connect the HDS to the DLC.

?2.
Turn the vehicle to the ON mode. Make sure the A/C system is OFF, then start the engine.

?3.
Turn the fan control dial ON, then momentarily turn ON the A/C with the A/C button.
NOTE: Do not run the A/C for more than a few seconds with the engine running or damage to the A/C system will result.

?4.
Check the parameter(s) below with the HDS.
Signal
Threshold
Current conditions
Values
Unit
Values
Unit
FAN LOW CTRL
ON
      

Is the FAN LOW CTRL on with the A/C on?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
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.?
3.
Radiator fan and fan control relays check:

Radiator fan and fan control relays check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Remove the radiator fan relay and the fan control relay from the under-hood fuse/relay box, and test it.

Are the relays OK?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Replace the radiator fan relay and/or the fan control relay.?
4.
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
Fan control relay: disconnected
Test point 1
Radiator fan relay 4P socket No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B MAIN FAN wire is OK. Go to step 5.
     
NO
     
     
     
An open in the +B MAIN FAN wire. Replace the under-hood fuse/relay.?
5.
Determine possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit):

Determine possible failure area (radiator fan relay switch side circuit, radiator fan relay coil side circuit)
?1.
Reinstall the fan control relay.

?2.
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


Do the A/C condenser and radiator fans run on low?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
Go to step 8.
6.
Open wire check (IG2 A/C line):

Open wire check (IG2 A/C line)
?1.
Disconnect the jumper wire.

?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
Test point 1
Radiator fan relay 4P socket No. 3
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The IG2 A/C wire is OK. Go to step 7.
     
NO
     
     
     
Repair an open in the wire between the No. C24 (7.5 A) fuse in the under-dash fuse/relay box and the radiator fan relay. If the wire is OK, replace the under-dash fuse/relay box.?
7.
Open wire check (FAN LO SIGNAL line):

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

?2.
Reinstall the radiator fan relay.

?3.
Jump the SCS line with the HDS.

NOTE: This step must be done to protect the PCM from damage.

?4.
Disconnect the following connector.
PCM connector A (51P)

?5.
Connect terminals A and B with a jumper wire.
Terminal A
PCM connector A (51P) No. 22
Terminal B
Body ground

?6.
Turn the vehicle to the ON mode.

Do the A/C condenser and radiator fans run on low?

     
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 wire between the radiator fan relay and the PCM.?
8.
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.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Radiator fan motor 2P connector: disconnected
Radiator fan relay 4P socket No. 1 and No. 2: jumped
Test point 1
Radiator fan motor 2P connector No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The MAIN FAN MOTOR wire is OK. Go to step 9.
     
NO
     
     
     
Repair an open in the wire between the radiator fan relay and the radiator fan motor.?
9.
Radiator and A/C condenser fan motors test:

Radiator and A/C condenser fan motors test
?1.
Test the radiator and the A/C condenser fan motors.

Are the radiator and A/C condenser fan motors OK?

     
YES
     
     
     
Go to step 10.
     
NO
     
     
     
10.
Open wire check (FAN HI/LO RLY COM line):

Open wire check (FAN HI/LO RLY COM line)
?1.
Reconnect the radiator fan motor 2P connector.

?2.
Remove the fan control relay from the under-hood fuse/relay box.

?3.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Radiator fan relay: disconnected
Fan control relay: disconnected
Radiator fan relay 4P socket No. 1 and No. 2: jumped
Test point 1
Fan control relay 5P socket No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The FAN HI/LO RLY COM wire is OK. Go to step 11.
     
NO
     
     
     
Repair an open in the wire between the radiator fan motor and the fan control relay.?
11.
Open wire check (SUB FAN MOTOR line):

Open wire check (SUB FAN MOTOR line)
?1.
Reinstall the fan control relay.

?2.
Disconnect the following connector.
A/C condenser fan motor 2P connector

?3.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Radiator fan relay: disconnected
 
A/C condenser fan motor 2P connector: disconnected
 
Radiator fan relay 4P socket No. 1 and No. 2: jumped
Test point 1
A/C condenser fan motor 2P connector No. 1
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
Check for an open in the wire between the A/C condenser fan motor and body ground. If the wire is OK, check for poor ground at G301.?
     
NO
     
     
     
Repair an open in the wire between the fan control relay and the A/C condenser fan motor.?