DTC B2179: Driver's Door Key Cylinder Switch LOCK/UNLOCK Signal Error

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.

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0), and then back ON (II).
Turn the driver's door key cylinder to the LOCK and UNLOCK positions with the ignition key.
Check for DTCs with the HDS.
Is DTC B2179 indicated?

YES - Go to step 5.

NO - Intermittent failure, the driver's door key cylinder switch system is OK at this time. Check for loose or poor connections.
With the driver's door key cylinder switch in neutral position, select DOOR LOCK from the BODY ELECTRICAL system select menu, and enter the DATA LIST.
Check the ON/OFF Information of the Driver's Door Key Cylinder Switch (LOCK) and Driver's Door Key Cylinder Switch (UNLOCK) in the DATA LIST.
Are both information indicators OFF?

YES - Go to step 7.

NO - Go to step 8.
Turn the driver's door key cylinder to the LOCK and UNLOCK positions with the ignition key, and check the ON/OFF information of the Driver's Door Key Cylinder Switch (LOCK) and Driver's Door Key Cylinder Switch (UNLOCK) in the DATA LIST.
Are both Driver's Door Key Cylinder Switch (LOCK) and Driver's Door Key Cylinder Switch (UNLOCK) information indicators ON at the same time with the door key cylinder switch in the LOCK or UNLOCK position?

YES - Test the key cylinder switch (see DOOR KEY CYLINDER SWITCH TEST ). If it is OK, repair the short between the No. 8 BLU and No. 9 LT BLU wires.

NO - Replace the driver's MPCS unit.
Disconnect the driver's door lock actuator 10P connector.
Check the ON/OFF information of the Driver's Door Key Cylinder Switch (LOCK) and Driver's Door Key Cylinder Switch (UNLOCK) in the DATA LIST.
Are both information indicators OFF?

YES - Faulty driver's door key cylinder switch; replace the driver's door lock actuator assembly.

NO - Go to step 10.
Turn the ignition switch to LOCK (0).
Disconnect driver's MPCS unit connector A (40P).
Check for continuity between body ground and the driver's door lock actuator 10P connector No. 8 and No. 9 terminals individually.

Fig 1: Identifying Continuity Between Driver's Door Lock Actuator 10P Connector No. 8 And No. 9 Terminals And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to ground in the wire.

NO - Replace the driver's MPCS unit.