Ground Circuits
WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 1991 Pontiac Sunbird, 1991 Pontiac Grand Prix, 1991 Pontiac Grand Am, 1991 Pontiac Firebird, and 1991 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
- Using an ohmmeter, check for continuity to ground on control unit ground terminals. Use appropriate schematic in WIRING DIAGRAMS article to determine ECM ground terminals. Resistance to ground should be zero ohms. If reading is other than zero ohms, repair open to ground.
- Using a DVOM, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If voltmeter reading is one volt or more, check for open, corrosion or loose connection on ground lead.