DTC B1128: Driver's Door Remote Switch Input Circuit Malfunction (Simultaneous input of lock and unlock signal)

WARNING: This page is about a different car, the 2011 Honda Insight and 2010 Honda Insight. 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.
Lock and unlock the driver's door with the driver's door lock switch.
Check for DTCs with the HDS.
Is DTC B1128 indicated?

YES -Go to step 4.

NO -Intermittent failure, the driver's door lock switch system is OK at this time. Check for loose or poor connections.
With the driver's door lock switch in the neutral position, select KEYLESS TRANSMITTER from the HDS and enter the DATA LIST.
Check the ON/OFF information of the DRIVER'S DOOR LOCK SWITCH (LOCK) and DRIVER'S DOOR LOCK SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?

YES -Check the wires for continuity between the under-dash fuse/relay box and the driver's door key cylinder switch. If there is continuity, the MICU is faulty. Replace the under-dash fuse/relay box.
- USA models (see REMOVAL AND INSTALLATION ).
- Canada models (see CANADA MODELS ).
NO -Go to step 6.
Disconnect the power window master switch connector.
Check the ON/OFF information of the DRIVER'S DOOR LOCK SWITCH (LOCK) and DRIVER'S DOOR LOCK SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?

YES -Faulty door lock switch; replace the power window master switch (see POWER WINDOW MASTER SWITCH REPLACEMENT ).

NO -Go to step 8.
Turn the ignition switch to LOCK (0).
Disconnect under-dash fuse/relay box connector E (12P).
Check for continuity between body ground under-dash fuse/relay box connector E (12P) terminals No. 8 (LOCK) and No. 1 (UNLOCK) individually.

Fig 1: Checking Continuity Between Body Ground Under-Dash Fuse/Relay Box Connector E (12P) Terminals No. 8 And No. 1
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the LOCK or UNLOCK wire.

NO -Go to step 11.
Check for continuity between under-dash fuse/relay box connector E (12P) terminals No. 8 (LOCK) and No. 1 (UNLOCK).

Fig 2: Checking Continuity Between Under-Dash Fuse/Relay Box Connector E (12P) Terminals No. 8 (Lock) And No. 1 (Unlock)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between the LOCK and UNLOCK wires.

NO -Faulty MICU, replace the under-dash fuse/relay box.
- USA models (see REMOVAL AND INSTALLATION ).
- Canada models (see CANADA MODELS ).