B1127

DTC Troubleshooting: B1127

DTC B1127:

Driver's Door Key Cylinder Switch Input Circuit Malfunction (Simultaneous input of lock and unlock signal)

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. Insert the ignition key into the driver's door key cylinder switch, and turn the key in LOCK and UNLOCK positions at least ten times.

4. Check for DTCs with the HDS.

Is DTC B1127 indicated?

YES -

Go to step 5.

NO -

Intermittent failure, the driver's door key cylinder switch system is OK at this time.�

5. With the driver's door key cylinder in the neutral position, select KEYLESS TRANSMITTER from the BODY ELECTRICAL SYSTEM SELECT menu, and enter 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 12.

NO -

Go to step 7.

7. Disconnect the driver's door lock actuator 10P connector.

8. 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 latch assembly Service and Repair.�

NO -

Go to step 9.

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

10. Disconnect under-dash fuse/relay box connector T (34P).

11. Check for continuity between under-dash fuse/relay box connector T (34P) terminals No. 31 (UNLOCK) and No. 32 (LOCK) and body ground individually.





Is there continuity?

YES -

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

NO -

Faulty MICU; replace the under-dash fuse/relay box Under-dash Fuse/Relay Box Removal/Installation.�

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

13. Disconnect the driver's door lock actuator 10P connector.

14. Disconnect under-dash fuse/relay box connector T (34P).

15. Check for continuity between under-dash fuse/relay box connector T (34P) terminals No. 31 (UNLOCK) and No. 32 (LOCK).





Is there continuity?

YES -

Repair a short between the LOCK and UNLOCK wires.�

NO -

Substitute a known-good MICU Under-dash Fuse/Relay Box Removal/Installation, and recheck. If the symptom/indication goes away, the original MICU is faulty; replace the under-dash fuse/relay box Under-dash Fuse/Relay Box Removal/Installation, if not, replace the driver's door latch assembly Service and Repair.�