Diagnostic Aids

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS in Wiring Systems.
The table below shows the ignition switch positions and the corresponding states of the circuits.

Fig 1: Ignition Switch Positions & Corresponding States Of Circuits
Courtesy of GENERAL MOTORS CORP.