DTC B1239 or DTC indicator A: An Open or Short in the Front Mode Control Motor Circuit

WARNING: This page is about a different car, the 2009 Acura MDX, 2008 Acura MDX, and 2007 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

Clear the DTC with the HDS.
Turn the ignition switch to LOCK (0), and then ON (II).
Do the self-diagnostic with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ) or climate control unit (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
Check for DTCs.
Is DTC B1239 or A indicated?

YES - Go to step 5.

NO - Intermittent failure, check for loose wires or poor connections on the front mode control motor circuit.
Turn the ignition switch to LOCK (0).
Test the front mode control motor (see FRONT MODE CONTROL MOTOR TEST ).
Is the front mode control motor OK?

YES - Go to step 7.

NO - Replace the front mode control motor (see FRONT MODE CONTROL MOTOR REPLACEMENT ).
Disconnect the front mode control motor 7P connector.
Disconnect climate control unit connector A (40P).

Check for continuity between the following terminals of climate control unit connector A (40P) and the front mode control motor 7P connector.

40P	7P
No. 8	No. 7
No. 31	No. 6
No. 32	No. 5
No. 33	No. 4
No. 34	No. 3

Fig 1: Identifying Continuity Between Climate Control Unit A (40P) And Front Mode Control Motor 7P Connector Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 10.

NO - Repair open in the wire(s) between the climate control unit and the front mode control motor.

Check for continuity between body ground and climate control unit connector A (40P) No. 31,32, 33, and 34 terminals individually.

Fig 2: Identifying Continuity Between Body Ground And Climate Control Unit Connector A (40P) No. 31,32, 33, And 34 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to body ground in the wire(s) between the climate control unit and the front mode control motor.

NO - Go to step 11.

Check for continuity between climate control unit connector A (40P) terminals as follows.

TERMINALS REFERENCE CHART

From terminal	To terminals
31	32, 33, 34
32	33, 34
33	34

Is there continuity between any of the terminals?

YES - Repair the short in the wires.

NO - Go to step 12.

Turn the ignition switch to ON (II), and check the same terminals for voltage to body ground.

Fig 3: Identifying Same Terminals For Voltage To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage?

YES - Repair short to power in the wire(s) between the climate control unit and the front mode control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit.

NO - Check for loose wires or poor connections at climate control unit connector A (40P) and at the front mode control motor 7P 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.