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 G502.
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 heater control panel connector A (14P).
13. Check for continuity between the No. 7 and No. 8 terminals of heater control panel connector A (14P) 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.
NO - Go to step 14.
14. Check for continuity between the following terminals of heater control panel connector A (14P) and power transistor 4P connector.
14P: 4P:
No. 7 No. 4
No. 8 No. 2
Is there continuity?
YES - Go to step 15.
NO - Repair any open in the wire(s) between the heater control panel and the power transistor.
15. Reconnect, heater control panel connector A (14P).
16. Test the power transistor.
Is the power transistor OK?
YES - Check for loose wires or poor connections at heater control panel connector A (14P) 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.
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 wire between the No. 14 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.