Shorted Communication Line Test

WARNING: This page is about a different car, the 2008 Honda Pilot, 2007 Honda Pilot, and 2006 Honda Pilot. However, it is still accessible from the selected car via links, so may be relevant.

Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
Carefully pry off the driver's door switch trim (see step 5 in FRONT DOOR PANEL REMOVAL/INSTALLATION )
Disconnect door multiplex connector A (20P).
Disconnect passenger's multiplex control unit connector B (22P).
Check for continuity between No. 15 terminal of door multiplex connector A (20P) and body ground.

Fig 1: Checking Continuity Between No 15 Terminal Of Door Multiplex Connector A (20P) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to ground in the wire between door multiplex control unit connector and body ground.

NO - Go to step 6.
Check for continuity between B9 terminal of passenger's multiplex connector B (22P) and body ground.

Fig 2: Checking Continuity Between B9 Terminal Of Passenger's Multiplex Connector B (22P) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to ground in the wire between passenger's multiplex control unit connector and driver's multiplex control unit connector.

NO - Replace driver's multiplex control unit and recheck the symptom.