Blower Motor Circuit Troubleshooting
Blower Motor Circuit Troubleshooting
1.
Blower motor operation check 1:

Blower motor operation check 1
?1.
Turn the vehicle to the ON mode and the fan control dial to MAX.

Does the blower motor run at high speed?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Go to step 7.
2.
Blower motor operation check 2:

Blower motor operation check 2
?1.
Turn the fan control dial to OFF.

?2.
Make sure the vehicle in ON mode.

Does the blower motor run?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Go to step 15.
3.
Shorted wire check (BLOWER HI/BLOWER MTR(H) line):

Shorted wire check (BLOWER HI/BLOWER MTR(H) line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connectors.
Blower motor 2P connector
Blower resistor 4P connector
Heater fan switch 8P connector

?3.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor 2P connector: disconnected
Blower resistor 4P connector: disconnected
Heater fan switch 8P connector: disconnected
Test point 1
Heater fan switch 8P connector No. 2
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short to ground in the wire between the blower motor, the blower resistor, and the heater fan switch.?
     
NO
     
     
     
The BLOWER HI/BLOWER MTR(H) wire is not shorted. Go to step 4.
4.
Shorted wire check (BLOWER MID1/BLOWER MTR(M1) line):

Shorted wire check (BLOWER MID1/BLOWER MTR(M1) line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor 2P connector: disconnected
Blower resistor 4P connector: disconnected
Heater fan switch 8P connector: disconnected
Test point 1
Heater fan switch 8P connector No. 3
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short to ground in the wire between the blower resistor and the heater fan switch.?
     
NO
     
     
     
The BLOWER MID1/BLOWER MTR(M1) wire is not shorted. Go to step 5.
5.
Shorted wire check (BLOWER LOW/BLOWER MTR(L) line):

Shorted wire check (BLOWER LOW/BLOWER MTR(L) line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor 2P connector: disconnected
Blower resistor 4P connector: disconnected
Heater fan switch 8P connector: disconnected
Test point 1
Heater fan switch 8P connector No. 5
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short to ground in the wire between the blower resistor and the heater fan switch.?
     
NO
     
     
     
The BLOWER LOW/BLOWER MTR(L) wire is not shorted. Go to step 6.
6.
Shorted wire check (BLOWER MID2/BLOWER MTR(M2) line):

Shorted wire check (BLOWER MID2/BLOWER MTR(M2) line)
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor 2P connector: disconnected
Blower resistor 4P connector: disconnected
Heater fan switch 8P connector: disconnected
Test point 1
Heater fan switch 8P connector No. 7
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short to ground in the wire between the blower resistor and the heater fan switch.?
     
NO
     
     
     
The BLOWER MID2/BLOWER MTR(M2) wire is not shorted. Replace the heater fan switch.?
7.
Fuse check:

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

?2.
Check the following fuses.
Fuse
No. C24 (7.5 A)
Location
Under-dash fuse/relay box

Fuse
No. D3 (30 A)
Location
Auxiliary under-dash fuse box

Are the fuses OK?

     
YES
     
     
     
Go to step 8.
     
NO
     
     
     
Replace the fuse(s), and recheck. If the fuse(s) blows again, check for a short in the No. C24 (7.5 A) and/or No. D3 (30 A) fuse circuit(s).?
8.
Blower motor relay check:

Blower motor relay check
?1.
Remove the blower motor relay from the under-dash relay holder A, and test it.

Is the relay OK?

     
YES
     
     
     
Go to step 9.
     
NO
     
     
     
Replace the blower motor relay.?
9.
Open wire check (+B HTR MTR line):

Open wire check (+B HTR MTR line)
?1.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor relay: disconnected
Test point 1
Blower motor relay 4P socket No. 3
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The +B HTR MTR wire is OK. Go to step 10.
     
NO
     
     
     
Repair an open in the wire between the No. D3 (30 A) fuse in the auxiliary under-dash fuse box and the blower motor relay.?
10.
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
Blower motor relay: disconnected
Test point 1
Blower motor relay 4P socket No. 7
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
The IG2 A/C wire is OK. Go to step 11.
     
NO
     
     
     
Repair an open in the wire between the No. C24 (7.5 A) fuse in the under-dash fuse/relay box and the blower motor relay. If wire is OK, replace the under-dash fuse/relay box.?
11.
Open wire check (GND line):

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

?2.
Check for the continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Blower motor relay: disconnected
Test point 1
Blower motor relay 4P socket No. 8
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
The GND wire is OK. Go to step 12.
     
NO
     
     
     
Check for an open in the wire between the blower motor relay and body ground. If the wire is OK, check for poor ground at G403.?
12.
Determine possible failure area (blower motor, others):

Determine possible failure area (blower motor, others)
?1.
Reinstall the blower motor relay.

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Blower motor 2P connector No. 1
Terminal B
Body ground


?3.
Turn the vehicle to the ON mode.

Does the blower motor run?

     
YES
     
     
     
Go to step 13.
     
NO
     
     
     
Go to step 17.
13.
Heater fan switch check:

Heater fan switch check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the jumper wire.

?3.
Disconnect the following connector.
Heater fan switch 8P connector

?4.
Test the heater fan switch.

Is the heater fan switch OK?

     
YES
     
     
     
Go to step 14.
     
NO
     
     
     
14.
Open wire check (BLOWER HI/BLOWER MTR(H) line):

Open wire check (BLOWER HI/BLOWER MTR(H) line)
?1.
Connect terminals A and B with a jumper wire.
Terminal A
Heater fan switch 8P connector No. 2
Terminal B
Body ground


?2.
Turn the vehicle to the ON mode.

Does the blower motor run?

     
YES
     
     
     
Check for an open in the wire between the heater fan switch and body ground. If the wire is OK, check for poor ground at G403.?
     
NO
     
     
     
Repair an open in the wire between the blower motor and the heater fan switch.?
15.
Blower resistor check:

Blower resistor check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connector.
Blower resistor 4P connector

?3.
Test the blower resistor.

Is the blower resistor OK?

     
YES
     
     
     
Go to step 16.
     
NO
     
     
     
16.
Blower motor operation check 3:

Blower motor operation check 3
?1.
Reconnect the blower resistor 4P connector.

?2.
Disconnect the following connector.
Heater fan switch 8P connector

?3.
Connect terminals A and B with a jumper wire.
NOTE: Connect the jumper wire one by one.

Terminal A
Heater fan switch 8P connector No. 5
Terminal B
Body ground

Terminal A
Heater fan switch 8P connector No. 3
Terminal B
Body ground

Terminal A
Heater fan switch 8P connector No. 7
Terminal B
Body ground

Terminal A
Heater fan switch 8P connector No. 2
Terminal B
Body ground


?4.
Turn the vehicle to the ON mode.

Does the blower motor speed change properly?

     
YES
     
     
     
     
NO
     
     
     
Repair any open or cause of excessive resistance in the appropriate wire(s) between the blower motor, the blower resistor, and the heater fan switch.?
17.
Open wire check (BLOWER MTR line):

Open wire check (BLOWER MTR line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the jumper wire.

?3.
Disconnect the following connector.
Blower motor 2P connector

?4.
Turn the vehicle to the ON mode.

?5.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle ON mode
Blower motor 2P connector: disconnected
Test point 1
Blower motor 2P connector No. 2
Test point 2
Body ground


Is there battery voltage?

     
YES
     
     
     
     
NO
     
     
     
Check for an open in the wire between the blower motor relay and the blower motor.?