Diagnostic Procedures (Grand Prix, Impala, Monte Carlo & Park Avenue)

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: DTC P1639: 5-Volt Reference Circuit "B" Or No. 2 (Steps 1-5)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC P1639: 5-Volt Reference Circuit "B" Or No. 2 (Steps 6-10)

Courtesy of GENERAL MOTORS CORP.