B1278 Code: Meaning, Causes, and Symptoms | OBD2 Codes
B1278 – Headlight Switch ON Position Circuit Malfunction
B1278 Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
B1278 Possible Causes
Faulty Combination Headlight Switch,Combination Headlight Switch harness is open or shorted,Combination Headlight Switch circuit poor electrical connection,Faulty Multiplex Integrated Control Unit (MICU)
The Multiplex Integrated Control Unit (MICU) monitors the Headlight Switch Position. The MICU sets the OBDII code when the Headlight Switch Position is not to factory specifications.