Diagnostic Aids

If the DTC B2587 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 control circuit of the park lamp relay
- The park lamp relay
- The BCM
Fig 1: DTC B2587 Diagnosis (Steps 1-7)
Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2587 Diagnosis (Steps 8-13)
Courtesy of GENERAL MOTORS CORP.