usually...gm wiring systems positive cable goes to the starter first....when you turn your key on it picks up juice from the starter (smaller red selenoid wire) goes to the back of the alternator...this feeds the inside of the vehicle 12 volts....start there...usually a fusable link (in line fuse) on the red selenoid wire can be burnt out and not feeding the back of the alternator when key is on. try this. a test light will test the wiring and fusable link. test juice to the starter first...then each side of fusable link.....then red heavy wire at back of alternator. Key in the on position....on occassion ignition switches have gone bad?
Jul 18, 2010 Rating
Check battery leads by: Anonymous
Start tracing out battery leads and grounds. You need to use a volt meter and check for power and ground at every point along the system starting from the battery.