DTC Troubleshooting: 12

DTC 12:  A Problem in the Blower Motor Circuit

1.Check the No. 11 (40 A) fuse in the under-hood fuse/relay box, and the No. 14 (10 A) 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 G501.n


8.Connect the No. 2 and No. 4 terminals 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 the heater control panel 36P connector.

13.Check for continuity between the No. 20 and No. 21 terminals of the heater control panel 36P connector and body ground individually.

 

Is there continuity?


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


NO - Go to 14.


14.Check the continuity between the following terminals of the heater control panel 36P connector and the power transistor 4P connector.

36P: 4P: 
No. 20 No. 3 
No. 21 No. 1 

 

Is there continuity?


YES - Go to 15.


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

15.Reconnect the heater control panel 36P connector.

16.Test the power transistor.

Is the power transistor OK?


YES - Check for loose wires or poor connections at the heater control panel 36P connector and at the power transistor 4P connector. If the connections are good, substitute a known-good heater control panel, and recheck. If the symptom/indication goes away, replace the original heater control panel.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 under-hood fuse/relay box, and test it.

Is the 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 4P socket and body ground.

 

Is there battery voltage?


YES - Go to 23.


NO - Replace the under-hood fuse/relay box.n


23.Turn the ignition switch ON (II).

24.Measure the voltage between the No. 4 terminal of the blower motor relay 4P socket and body ground.

 

Is there battery voltage?


YES - Go to 25.


NO - Repair open in the wire between the No. 14 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 4P socket and body ground.

 

Is there continuity?


YES - Repair open in the BLU/WHT 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 G201.n