DTC Troubleshooting: B1127
DTC B1127:
 Driver's Door Key Cylinder Switch Signal Error (LOCK/UNLOCK)
  1. Clear the DTCs with the HDS.
  1. Turn the ignition switch to LOCK (0) and then back to ON (II).
  1. Insert the ignition key into the driver's door key cylinder switch, and turn the key to the LOCK and UNLOCK positions 10 times.
  1. Check for DTCs with the HDS.
Is DTC B1127 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, the system is OK at this time. Check for loose or poor connections.■
  1. With the driver's door key cylinder in the neutral position, select KEYLESS with the HDS, and enter the DATA LIST.
  1. 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?
YES -
Go to Step 12 .
NO -
Go to Step 7 .
  1. Disconnect the driver's door lock actuator 10P connector.
  1. 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?
YES -
Faulty driver's door key cylinder switch ; replace the driver's door lock actuator.■
NO -
Go to Step 9 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the door multiplex control unit 37P connector.
  1. Check for continuity between body ground and the door multiplex control unit 37P connector No. 28 and No. 29 terminals.
Is there continuity?
YES -
Repair a short to ground in the wire.■
NO -
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the driver's door lock actuator 10P connector.
  1. Disconnect the door multiplex control unit 37P connector.
  1. Check for continuity between the door multiplex control unit 37P connector No. 28 and No. 29 terminals.
Is there continuity?
YES -
Repair a short between the LOCK and UNLOCK wires.■
NO -
Substitute a known-good power window master switch. If the symptom goes away, replace the original power window master switch. If not, replace the driver's door lock actuator.■