B1127

DTC Troubleshooting: B1127

DTC B1127: Driver's Door Key Cylinder Switch Input Circuit Malfunction

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A. Troubleshooting - B-CAN System Diagnosis Test Mode A

1. Clear the DTCs with the HDS.

2. Turn the ignition switch to LOCK (0) and then back to ON (II).

3. Operate the driver's door key cylinder several times.

4. 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.


5. With the driver's door key cylinder in the neutral position, select SECURITY from the BODY ELECTRICAL system select menu with the HDS, and enter the DATA LIST.

6. 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 7.

NO - Go to step 8.


7. 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.

Are both DRIVER'S DOOR KEY CYLINDER SWITCH (LOCK) and DRIVER'S DOOR KEY CYLINDER SWITCH (UNLOCK) information indicators ON at the same time with the door key cylinder switch in the LOCK or UNLOCK position?
YES - Test the key cylinder switch. Door Key Cylinder Switch Test If it is OK, repair the short between the wires.

NO - Replace the driver's MPCS unit.


8. Remove the driver's door panel. Service and Repair

9. Disconnect the driver's door key cylinder switch 3P connector.

10. 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 - Replace the driver's door key cylinder switch.

NO - Go to step 11.


11. Turn the ignition switch to LOCK (0).

12. Disconnect the door multiplex control unit 23P connector.

13. Check for continuity between terminals No. 1 (UNLOCK) and No. 3 (LOCK) of the driver's door key cylinder switch 3P connector and body ground.

Is there continuity?
YES - Repair a short to ground in the wire.

NO - Faulty door multiplex control unit; replace the power window master switch.