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 headlight switch to the PARKING (PARKING LIGHT) and ON (low beam) position, and then OFF position.

4. Clear the DTCs with the HDS.

Are DTCs B1275, B1276, or B1278 indicated?

YES -

Go to step 5.

NO -

Intermittent failure, the 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 each combination light switch position value with the DATA LIST menu.

When the combination light switch is turned OFF





When the combination light switch is turned to PARKING (SMALL)





When the combination light switch is turned ON (HEADLIGHT)





Are all data list values correct?

YES -

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

NO -

Go to step 7.

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

8. Disconnect the combination light switch 12P connector.

9. Turn the ignition switch to ON (II).

10. Select LIGHTING from the BODY ELECTRICAL system select menu, and enter DATA LIST.

11. Check each combination light switch position value with the DATA LIST menu.

When the combination light switch is turned OFF





Are all data list values indicated OFF?

YES -

Go to step 15.

NO -

Go to step 12.

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

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

14. 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/Installation.�

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

16. Do the combination light switch test Service and Repair.

Is the combination light switch OK?

YES -

Go to step 17.

NO -

Replace the combination light switch Service and Repair.�

17. Disconnect under-dash fuse/relay box connectors S (20P).

18. Check for continuity between the under-dash fuse/relay box connector S (20P) terminals and the combination light switch 12P connector terminals as shown:









Is there continuity?

YES -

Go to step 19.

NO -

Repair an open in the wire.�

19. Check for continuity between under-dash fuse/relay box connector S (20P) terminals as shown:





Is there continuity?

YES -

Repair a short between the wires.�

NO -

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