DTC B2181: Driver's Door Lock Knob 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 driver's door with the door lock knob switch.
Check for DTCs with the HDS.
Is DTC B2181 indicated?

YES - Go to step 5.

NO - Intermittent failure, the driver's door lock knob switch system is OK at this time. Check for loose or poor connections.
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 Lock Knob Switch (LOCK) and Driver's Door Lock Knob Switch (UNLOCK) in the DATA LIST.
Does the Driver's Door Lock Knob Switch (LOCK) information indicate ON and Driver's Door Lock Knob Switch (UNLOCK) information indicate OFF with the door lock knob switch is in the LOCK position, and does the Driver's Door Lock Knob Switch (LOCK) information indicate OFF and Driver's Doer Lock Knob Switch (UNLOCK) information indicate ON with the door lock knob switch is in the UNLOCK position?

YES - Replace the driver's MPCS unit.

NO - Go to step 7.
Disconnect the driver's door lock actuator 10P connector.
Check the ON/OFF information of the Driver's Door Knob Switch (LOCK) and Driver's Door Lock Knob Switch (UNLOCK) in the DATA LIST.
Are both information indicators OFF?

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

NO - Go to step 9.
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. 6 and No. 7 terminals individually, individually.

Fig 1: Identifying Continuity Between Driver'S Door Lock Actuator 10P Connector No. 6 And No. 7 Terminals And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Replace the driver's MPCS unit.