Electronic Climate Control
DTC B1223 or DTC indicator L: A Problem in the Rear Blower Motor Circuit1. Clear the DTC by turning the ignition switch OFF, and then ON (II).
2. Operate the climate control system in several modes.
3. Check for DTCs using the HDS or self-diagnostic.
Is DTC B1223 or L indicated?
YES - Go to step 4.
NO - Intermittent failure, check for loose wires or poor connections on the rear blower motor circuit.
4. Turn the ignition switch OFF.
5. Check the No. 22 (70 A) fuse in the under-hood fuse/relay box, and the No. 1 (30 A) fuse in the passenger's under-dash fuse/relay box.
Are the fuses OK?
YES - Go to step 6.
NO - Replace the fuse(s), and recheck.
6. Connect the No. 2 terminal of the rear blower motor 2P connector to body ground with a jumper wire.
7. Turn the ignition switch ON (II).
Does the rear blower motor run?
YES - Go to step 8.
NO - Go to step 23.
8. Turn the ignition switch OFF.
9. Disconnect the jumper wire.
10. Disconnect the power transistor 4P connector.
11. Check for continuity between the No. 2 terminal of the rear power transistor 4P connector and body ground.
Is there continuity?
YES - Go to step 12.
NO - Check for an open in the BLK wire between the rear power transistor and body ground. If the wire is OK, check for poor ground at G652.
12. Connect the No. 2 and No. 4terminals of the rear power transistor 4P connector with a jumper wire.
13. Turn the ignition switch ON (II).
Does the rear blower motor run at high speed?
YES - Go to step 14.
NO - Repair open in the BLU/BLK wire between the power transistor and the blower motor.
14. Turn the ignition switch OFF.
15. Disconnect the jumper wire.
16. Disconnect the rear climate control unit 22P connector.
17. Check for continuity between the No. 18 and No. 19 terminals of the rear climate control unit 22P connector and body ground individually.
Is there continuity?
YES - Repair any short to body ground in the wire(s) between the rear climate control unit and the power transistor.
NO - Go to step 18.
18. Check for continuity between the above terminals of the rear climate control unit 22P connector and rear power transistor 4P connector.
Is there continuity?
YES - Go to step 19.
NO - Repair any open in the wire(s) between the rear climate control unit and the rear power transistor.
19. Start the engine.
20. Check for voltage between the No. 18 and No. 19 terminals of the rear climate control unit 22P connector and body ground individually.
Is there voltage?
YES - Repair short to power in the wires.
NO - Go to step 21.
21. Reconnect the rear climate control unit 22P connector.
22. Test the rear power transistor.
Is the power transistor OK?
YES - Check for loose wire or poor connections at the rear climate control unit 22P connector and at the rear power transistor 4P connector. If the connections are good, substitute a known-good rear climate control unit, and recheck. If the symptom/indication goes away, replace the original rear climate control unit.
NO - Replace the rear power transistor.
23. Disconnect the jumper wire.
24. Disconnect the rear blower motor 2P connector.
25. Measure the voltage between the No. 1 terminal of the rear blower motor 2P connector and body ground.
Is there battery voltage?
YES - Replace the rear blower motor.
NO - Go to step 26.
26. Turn the ignition switch OFF.
27. Remove the rear blower motor relay from the rear junction box, and test it.
Is the relay OK?
YES - Go to step 28.
NO - Replace the rear blower motor relay.
28. Measure the voltage between the No. 1 and No. 4 terminals of the rear blower motor relay 4P socket and body ground individually.
Is there battery voltage?
YES - Go to step 29.
NO - Repair the open in the BLK/WHT wire between the passenger's under-fuse/relay box and the rear junction box control unit.
29. Turn the ignition switch ON (II).
30. Check for continuity between the No. 3 terminal of the rear blower motor relay 4P socket and body ground.
Is there continuity?
YES - Substitute a known-good rear junction box, and recheck. If the symptom/indication goes away, replace the original rear junction box.
NO - Check for an open in the wire between the rear blower motor relay and body ground. If the wire is OK, check for poor ground at G652.