DTC B1127: Driver's Door Key Cylinder Switch Signal Error

WARNING: This page is about a different car, the 2006 Honda Odyssey and 2005 Honda Odyssey. 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 OFF, and then back ON (II).
Operate the driver's door key cylinder several times.
Check for DTCs with the HDS.
Is DTC B1127 indicated?
1. YES - Go to step 5.
2. NO - Intermittent failure. The driver's door key cylinder system is OK at this time. Check for loose or poor connections.
With the driver's door key cylinder in the neutral position, select SECURITY with the HDS, and enter the DATA LIST.
Check the ON/OFF information of the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?
1. YES - Go to step 7.
2. NO - Go to step 8.
Turn the driver's door key cylinder to the LOCK and UNLOCK positions with the ignition key and check the ON/OFF information of the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) in the DATA LIST.
Is the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) (DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK)) information indicator ON when the key cylinder is in the LOCK (UNLOCK) position, and OFF when the key is returned to the neutral position?
1. YES - Substitute the door multiplex control unit and retest.
2. NO - Faulty driver's door key cylinder switch or short to ground on the WHT/BLU and/or WHT wire.
Disconnect the driver's door key cylinder switch 3P connector.
Check the ON/OFF information of the DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) in the DATA LIST.
Are both information indicators OFF?
1. YES - Faulty driver's door key cylinder switch.
2. NO - Go to step 10.
Turn the ignition switch OFF.
Disconnect the driver's door multiplex control unit 23P connector.
Check for continuity between the No. 3 (LOCK) and No. 1 (UNLOCK) terminals of the driver's door key cylinder switch 3P connector and body ground.

Fig 1: Checking Continuity Between No. 3 (LOCK) & 1 (UNLOCK) Terminals Of Driver's Door Key Cylinder Switch 3P Connector And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair a short in the WHT/BLU (LOCK) or WHT (UNLOCK) wire.
2. NO - Faulty door multiplex control unit; replace the power window master switch.