DTC B2186: Front Passenger's Door Lock 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).
Lock and unlock the front passenger's door with the door lock switch.
Check for DTCs with the HDS.
Is DTC B2186 indicated?

YES - Go to step 5.

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

YES - Go to step 7.

NO - Go to step 8.
Operate the front passenger's door lock switch in the LOCK and UNLOCK positions, and check the ON/OFF information of the Front Passenger's Door Lock Switch (LOCK) and Front Passenger's Door Lock Switch (UNLOCK).
Are both the Front Passenger's Door Lock Switch (LOCK) and Front passenger's Door Lock Switch (UNLOCK) information indicators ON at the same time when the door lock switch is in the LOCK or UNLOCK position?

YES - Repair short between the wires.

NO - Replace the front passenger's MPCS unit.
Disconnect the front passenger's door lock switch 5P connector.
Check the ON/OFF information of the Front Passenger's Door Lock Switch (LOCK) and Front Passenger's Door Lock Switch (UNLOCK).
Are both information indicators OFF?

YES - Faulty front passenger's door lock switch; replace it.

NO - Go to step 10.
Turn the ignition switch to LOCK (0).
Disconnect front passenger's MPCS unit connector A (28P).
Check for continuity between body ground and the front passenger's door lock switch 5P connector No. 3 and No. 4 terminals individually.

Fig 1: Identifying Continuity Between Body Ground And Front Passenger's Door Lock Switch 5P Connector No. 3 And No. 4 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Replace the front passenger's MPCS unit.