DTC B2178: Assistant's Power Window Motor B-Phase Pulse Signal Input Error

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 to ON (II).
Open and close the front passenger's power window by using the front passenger's power window switch manually.
Check for DTCs with the HDS.
Is DTC B2178 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections.
Open and close the front passenger's power window by using the power window master switch manually.
Does the window motor operate?

YES -Go to step 6.

NO -Test the front passenger's power window motor (see POWER WINDOW MOTOR TEST ). If the motor tests OK, go to step 6.
Select POWER WINDOWS from the BODY ELECTRICAL SYSTEM SELECT menu, and enter the DATA LIST.
Check the DETECT/NONE information of the Front passenger's window motor B-phase pulse signal in the DATA LIST.
Does the information indicator display DETECT while the window is moving, and display NONE when the window is stopped?

YES -Replace the front passenger's MPCS unit (see FRONT PASSENGER'S MPCS UNIT INPUT TEST/REPLACEMENT ).

NO -Go to step 8.
Check for DTCs with the HDS.
Is DTC B2177 also indicated?

YES -Go to step 15.

NO -Go to step 9.
Turn the ignition switch to LOCK (0).
Disconnect front passenger's MPCS unit connector B (14P).
Disconnect the 6P connector from the front passenger's power window motor.
Check for continuity between front passenger's MPCS unit connector B (14P) terminal No. 4 and front passenger's power window motor 6P connector terminal No. 4.

Fig 1: Checking Continuity Between Connector B (14P) Terminal No. 4 And 6P Connector Terminal No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 13.

NO -Repair an open or high resistance in the wire.
Check for continuity between front passenger's power window motor 6P connector terminal No. 4 and body ground.

Fig 2: Checking Continuity Between Front Passenger's Power Window Motor 6P Connector Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 14.
Test the front passenger's power window motor (see POWER WINDOW MOTOR TEST ).
Is the motor OK?

YES -Replace the front passenger's MPCS unit (see FRONT PASSENGER'S MPCS UNIT INPUT TEST/REPLACEMENT ).

NO -Faulty front passenger's window motor; replace front passenger's door regulator (see FRONT DOOR GLASS AND REGULATOR REPLACEMENT ).
Check for continuity between front passenger's MPCS unit connector B (14P) terminals No. 3 and No. 6 and the front passenger's power window motor 6P connector terminals No. 1 and No. 2 respectively.

Fig 3: Checking Continuity Between Connector B (14P) Terminals No. 3 And No. 6 And 6P Connector Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 16.

NO -Repair an open or high resistance in the wire.
Check for continuity between front passenger's power window motor 6P connector terminal No. 1 and body ground.

Fig 4: Checking Continuity Between Front Passenger's Power Window Motor 6P Connector Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Faulty front passenger's window motor; replace front passenger's door regulator (see FRONT DOOR GLASS AND REGULATOR REPLACEMENT ).