DTC 12
DTC 12: A Problem in the Blower Motor Circuit1. Check the No.12 (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 step 2.
NO - Replace the fuse(s), and recheck.
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 step 4.
NO - Go to step 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.3 terminal of the power transistor 4P connector and body ground.
Is there continuity?
YES - Go to step 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.
8. Connect the No.1 and No.3 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 step 10.
NO - Repair open in the wire between the power transistor and the blower motor.
10. Turn the ignition switch OFF.
11. Disconnect the jumper wire.
12. Disconnect the climate control unit 30P connector.
13. Check for continuity between the No.16 and No.17 terminals of the climate control unit 30P connector 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.
NO - Go to step 14.
14. Check for continuity between the above terminals of the climate control unit 30P connector and power transistor 4P connector.
Is there continuity?
YES - Go to step 15.
NO - Repair any open in the wire(s) between the climate control unit and the power transistor.
15. Reconnect the climate control unit 30P connector.
16. Test the power transistor.
Is the power transistor OK?
YES - Check for loose wires or poor connections at the climate control unit 30P connector 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.
NO - Replace the power transistor.
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.
NO - Go to step 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 step 22.
NO - Replace the blower motor relay.
22. Measure the voltage between the No.3 terminal of the blower motor relay 4P socket and body ground.
Is there battery voltage?
YES - Go to step 23.
NO - Replace the under-hood fuse/relay box.
23. Turn the ignition switch ON (II).
24. Measure the voltage between the No.2 terminal of the blower motor relay 4P socket and body ground.
Is there battery voltage?
YES - Go to step 25.
NO - Repair open in the BLK/YEL wire between the No.14(10 A) fuse in the under-dash fuse/relay box and the blower motor relay.
25. Turn the ignition switch OFF.
26. Check for continuity between the No.1 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.
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 G301.