DTC B1128: Driver's Door Lock Switch Signal 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 OFF, and then back ON (II).
Operate the driver's door lock switch LOCK/UNLOCK several times.
Check for DTCs with the HDS.
Is DTC B1128 indicated?

YES - Go to step 5.

NO - Intermittent failure. The driver's door lock system is OK at this time.
With the driver's door lock switch in the neutral position, select KEYLESS 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 - Go to step 12.

NO - Go to step 7.
Disconnect the power window master switch 22P 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.

NO - Go to step 9.
Turn the ignition switch to LOCK (0).
Disconnect under-dash fuse/relay box connector T (34P).
Check for continuity between the No. 28 and No. 27 terminals of under-dash fuse/relay box connector T (34P) and body ground.

Fig 1: Checking Continuity Between Terminals Of Under-Dash Fuse/Relay Box Connector T (34P) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the No. 27 or No. 28 terminal wire.

NO - Faulty MICU; replace the under-dash fuse/relay box.
Turn the ignition switch to LOCK (0).
Disconnect the power window master switch 22P connector.
Disconnect under-dash fuse/relay box connector T (34P).
Check for continuity between the No. 28 and No. 27 terminals of under-dash fuse/relay box connector T (34P).

Fig 2: Checking Continuity Between No. 28 And No. 27 Terminals Of Under-Dash Fuse/Relay Box Connector T (34P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short in the wire between the No. 27 or No. 28 terminal wire.

NO -Substitute a known-good power window master switch, and recheck. If the symptom/indication goes away, replace the original power window master switch. If not, the MICU is faulty, replace the under-dash fuse/relay box.