Actions Taken When the DTC Sets

When DTC B257A 00 is present on the headlamp switch headlamps OFF signal circuit, the park lamps are always ON in the AUTO position. The headlamp switch operates in all positions other than AUTO. The AUTO headlamp defeat is inoperative.
When DTC B257A 00 is present on the headlamp switch headlamps ON signal circuit, the park lamps are always ON. The low and high beam headlamps operate normally.
When DTC B257A 00 is present on the headlamp switch park lamps ON signal circuit, the low and high beam headlamps are inoperative in the PARK and HEAD positions. The automatic headlamps disable switch will turn the park lamps ON and OFF. The park lamps are always ON or always OFF in the AUTO, PARK, and HEAD positions.