DTC Troubleshooting: 12

DTC 12:  A Problem in the Blower Motor Circuit

1.Check the No. 5 (40A) fuse in the under-hood fuse/relay box, and the No. 22 (7.5A) fuse in the under-dash fuse/relay box.

Are the fuses OK?


YES - Go to 2.


NO - Replace the fuse(s), and recheck.n


2.Connect the No. 2 terminal of the blower motor 2P connector to body ground with a jumper wire.

 

3.Turn the ignition switch ON (II).

Does the blower motor run?


YES - Go to 4.


NO - Go to 17.


4.Turn the ignition switch OFF.

5.Disconnect the jumper wire.

6.Disconnect the power transistor 4P connector.

7.Check for continuity between the No. 2 terminal of the power transistor 4P connector and body ground.

 

Is there continuity?


YES - Go to 8.


NO - Check for an open in the wire between the power transistor and body ground. If the wire is OK, check for poor ground at G402.n


8.Connect the No. 2 and No. 4 termials of the power transistor 4P connector with a jumper wire.

 

9.Turn the ignition switch ON (II).

Does the blower motor run at high speed?


YES - Go to 10.


NO - Repair open in the wire between the power transistor and the blower motor.n


10.Turn the ignition switch OFF.

11.Disconnect the jumper wire.

12.Disconnect climate control unit connector B (16P).

13.Check for continuity between the No. 15 and No. 16 terminals of climate control unit connector B (16P) and body ground individually.

 

Is there continuity?


YES - Repair any short to body ground in the wire(s) between the  climate control unit and the power transistor.n


NO - Go to 14.


14.Check for continuity between the following terminals of climate control unit connector B (16P) and power transistor 4P connector.

16P: 4P: 
No. 15 No. 1 
No. 16 No. 3 

 

Is there continuity?


YES - Go to 15.


NO - Repair any open in the wire(s) between the  climate control unit and the power transistor.n

15.Reconnect climate control unit connector B (16P).

16.Test the power transistor.

Is the power transistor OK?


YES - Check for loose wires or poor connections at climate control unit connector B (16P) and at the power transistor 4P connector. If the connections are good, substitute a known-good  climate control unit, and recheck. If the symptom/indication goes away, replace the original  climate control unit.n


NO - Replace the power transistor.n


17.Disconnect the jumper wire.

18.Disconnect the blower motor 2P connector.

19.Measure the voltage between the No. 1 terminal of the blower motor 2P connector and body ground.

 

Is there battery voltage?


YES - Replace the blower motor.n


NO - Go to 20.


20.Turn the ignition switch OFF.

21.Remove the blower motor relay from the relay holber, and test it.

Is there relay OK?


YES - Go to 22.


NO - Replace the  blower motor relay.n

22.Measure the voltage between the No. 1 terminal of the blower motor relay 5P socket and body ground.

 

Is there battery voltage?


YES - Go to 23.


NO - Repair open in the wire between the No. 5 fuse in the under-hood fuse/relay box and the  blower motor relay.n


23.Turn the ignition switch ON (II).

24.Measure the voltage between the No. 5 terminal of the blower motor relay 5P socket and body ground.

 

Is there battery voltage?


YES - Go to 25.


NO - Repair open in the wire between the No. 22 fuse in the under-dash fuse/relay box and the  blower motor relay.n

25.Turn the ignition switch OFF.

26.Check for continuity between the No. 3 terminal of the blower motor relay 5P socket and body ground.

 

Is there contnuity?


YES - Repair open in the wire between the  blower motor relay and the blower motor.n


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 G402.n