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B1278




DTC Troubleshooting: B1275, B1276, B1278

DTC B1275:

Headlight OFF Position Circuit Malfunction

DTC B1276:

Headlight Switch Parking Position Circuit Malfunction

DTC B1278:

Headlight ON Position 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. Turn the combination light switch to the park position, the headlight position, then back to the off position.

4. Clear the DTCs with the HDS.

Are DTCs B1275, B1276 and/or B1278 indicated?

YES -

Go to step 5.

NO -

Intermittent failure. The lighting system is OK at this time. Check for loose or poor connections.

5. Select LIGHTING from the BODY ELECTRICAL SYSTEM SELECT menu, and enter DATA LIST.

6. Check the ON/OFF information of the HEADLIGHT SWITCH (OFF), HEADLIGHT SWITCH (PARKING), and HEADLIGHT SWITCH (HEADLIGHT).

Are the HEADLIGHT SWITCH (OFF) information indicator ON, HEADLIGHT SWITCH (PARKING) information indicator OFF, and HEADLIGHT SWITCH (HEADLIGHT) information indicator OFF with the combination light switch in OFF position, and are the HEADLIGHT SWITCH (OFF) information indicator OFF, HEADLIGHT SWITCH (PARKING) information indicator ON, and HEADLIGHT SWITCH (HEADLIGHT) information indicator OFF with the combination light switch in SMALL position, and are the HEADLIGHT SWITCH (OFF) information indicator OFF, HEADLIGHT SWITCH (PARKING) information indicator OFF, and HEADLIGHT SWITCH (HEADLIGHT) information indicator ON with the combination light switch in ON position?

YES -

Check for loose or poor connections at the connector. If all the connector tests prove OK, replace the under-dash fuse/relay box Under-Dash Fuse/Relay Box Removal and Installation.

NO -

Go to step 7.

7. Disconnect the 12P connector from the combination light switch.

8. Check the ON/OFF information of the HEADLIGHT SWITCH (OFF), HEADLIGHT SWITCH (PARKING), and HEADLIGHT SWITCH (HEADLIGHT) in the DATA LIST.

All the information indicators OFF?

YES -

Go to step 12.

NO -

Go to step 9.

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

10. Disconnect under-dash fuse/relay box connector S (20P).

11. Check for continuity between body ground and under-dash fuse/relay box connector S (20P) terminals No. 1, No. 11, and No. 13 individually.





Is there continuity?

YES -

Repair a short to ground in the wire.

NO -

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

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

13. Check the combination light switch Service and Repair.

Is the combination light switch OK?

YES -

Go to step 14.

NO -

Replace the combination light switch Service and Repair.

14. Disconnect under-dash fuse/relay box connector S (20P).

15. Check for continuity between under-dash fuse/relay box connector S (20P) terminals No. 1, No. 5, No. 11, and No. 13 and the combination light switch 12P connector terminals No. 9, No. 12, No. 10, and No. 11 respectively.





Is there continuity?

YES -

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

NO -

Repair an open or high resistance in the wire.