Power Circuits
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
- Using a voltmeter, check for battery voltage between ECM continuous power terminal(s) and ground. If battery voltage is not present, check for blown fuse or open fusible link. If okay, check for open in wire between ECM terminal and power source.
- Turn ignition on. Using a voltmeter, check for battery voltage between ECM ignition power terminals and ground. If battery voltage is not present, check IGN fuse. If fuse is okay, check for an open in wire between battery and ignition switch, and between ignition switch and ECM terminal. If okay, check for a defective ignition switch.
- Connect voltmeter between ground and ECM starter (crank) signal terminal. On vehicles with manual transmission/transaxle, depress clutch pedal. Turn ignition switch to START position. Battery voltage should be present ONLY when ignition switch is in START position.
- If voltage is not present, check CRANK fuse or fusible link between ignition switch and ECM terminal. If fuse or fusible link is okay, check for an open in wire between ignition switch and ECM terminal, or check for a defective ignition switch.