B1279

DTC B1279: Headlight Switch DIMMER Position Circuit Malfunction

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

1. Clear the DTCs with the HDS.
2. Turn the ignition switch OFF, and then back ON (II).
3. Turn the combination light switch ON.
4. Change the DIMMER switch from low beam to high beam.
5. Turn the combination light switch OFF, and then PASSING position.
6. Check the DTCs with the HDS.

Is DTC B1279 indicated?

YES - Go to step 7.

NO - Intermittent failure. The lighting system is OK at this time. Check for loose or poor connections.

7. Select LIGHTING from the BODY ELECTRICAL menu, and enter the DATA LIST.
8. Check the ON/OFF information of the HEADLIGHT SWITCH (HEADLIGHT), HEADLIGHT SWITCH (HIGH BEAM) and HEADLIGHT SWITCH (PASSING).

Are the HEADLIGHT SWITCH (HIGH BEAM) information indicator ON, HEADLIGHT SWITCH (PASSING) information indicator ON with the combination light switch in DIMMER position, and are the HEADLIGHT SWITCH (HEADLIGHT) information indicator OFF, HEADLIGHT SWITCH (HIGH BEAM) information indicator OFF and HEADLIGHT SWITCH (PASSING) information indicator OFF with the combination light switch in ON position?

YES - Faulty MICU; replace the under-dash fuse/relay box.

NO - Go to step 9.

9. Disconnect the 12P connector from the combination light switch.
10. Check the ON/OFF information of the HEADLIGHT SWITCH (HEADLIGHT), HEADLIGHT SWITCH (HIGH BEAM) and HEADLIGHT SWITCH (PASSING) in the DATA LIST.

All the information indicators OFF?

YES - Go to step 14.

NO - Go to step 11.

11. Turn the ignition switch OFF.
12. Disconnect the under-dash fuse/relay box connector S (20P).




13. Check for continuity between the body ground and under-dash fuse/relay box connector S (20P) terminals No. 11, No. 12, and No. 16 individually.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Faulty MICU; replace the under-dash fuse/relay box.

14. Turn the ignition switch OFF.
15. Check the combination light switch.

Is the combination light switch OK?

YES - Go to step 16.

NO - Faulty combination light switch; replace it.

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




17. Check for continuity between the under-dash fuse/relay box connector S (20P) No. 5, No. 11, No. 12, and No. 16 terminals and the combination light switch 12P connector No. 12, No. 10, No. 6, and No. 4 terminals.

Is there continuity?

YES - Faulty MICU; replace the under-dash fuse/relay box.

NO - Repair an open in the wire.