B121A

Control System DTCs

DTC Troubleshooting: B121A - (49)

DTC B121A or DTC indicator 49 : An Open in the Mode Control Motor Circuit

1. Problem verification:

Problem verification
-1. Clear the DTCs with the HDS.

-2. Turn the ignition switch to LOCK (0), and then back to ON (II).

-3. Do the self-diagnostic with the HDS or the climate control unit How To Troubleshoot The Climate Control System.

-4. Check for DTCs.

Is DTC B121A or 49 indicated?
-YES- Go to step 2.
-NO- Intermittent failure. Check for loose wires or poor connections on the mode control motor circuit.

2. DTC check:

DTC check
-1. Check for DTCs.

Is DTC B1233 or 40 and/or B2986 or 55 indicated?
-YES- Repair an open in the wire between the climate control unit and the mode control motor.
-NO- Go to step 3.

3. Open wire check (MODE-P line):

Open wire check (MODE-P line)
-1. Turn the ignition switch to LOCK (0).

-2. Connect terminals A and B with a jumper wire.

















-3. Turn the ignition switch to ON (II).

-4. Do the self-diagnostic with the HDS or the climate control unit How To Troubleshoot The Climate Control System.

-5. Check for DTCs.

Is DTC B121A or 49 indicated?
-YES- Repair an open in the wire between the climate control unit and the mode control motor.
-NO- The MODE-P wire is OK. Replace the mode control motor Mode Control Motor Removal and Installation.