Diagnostic Aids

WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

If the DTC B2578 is a history DTC, the fault may be intermittent. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .
The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to battery in the headlamp relay coil control circuit.
- The headlamp relay coil is intermittently shorted to battery.
- The BCM is intermittently shorted to battery.