B1278

DTC B1278: Headlight Switch 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.

1. Clear the DTCs with the HDS.
2. Turn the ignition switch OFF, and then back ON (II), and wait for 2 seconds.
3. Turn the parking (small) light switch ON and wait for 2 seconds.
4. Turn the headlight light switch (LOW) ON and wait for 2 seconds.
5. Change the dimmer switch position from low beam to high beam and wait for 2 seconds.
6. Check the DTCs with the HDS.

Is DTC B1278 indicated?

YES - Go to step 7.

NO - Intermittent failure, the combination switch and the control unit are OK at this time. Check pinfits and connections.

7. Turn the ignition switch OFF.
8. Disconnect the combination light switch 12P connector from the wiper/washer switch.
9. Perform the combination light switch test. Combination Light Switch

Is the combination light switch OK?

YES - Faulty combination switch control unit, replace the wiper/washer switch.

NO - Replace the combination light switch.