Diagnostic Aids

If the DTC B2577 is a history DTC, the fault may be intermittent. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .
An intermittent short to ground or an open in the following locations may cause an intermittent malfunction to occur:
- The low beam headlamp relay control circuit
- The headlamp relay control circuit
- The headlamp relay
- The BCM
Fig 1: DTC B2577 Diagnosis (Steps 1-6)
Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2577 Diagnosis (Steps 7-13)
Courtesy of GENERAL MOTORS CORP.