Back in '89 I had a '78 Cutlass that had the same problem. My buddy fixed the problem since he was having the same problem with his '83. All I can remember is that there was/is a wire that will short out near the alternator. I was 15 years old at the time and didn't pay any attention to what he did to fix it. Just know that it was fixed and that he then fixed several other cars with the same problem. Maybe this isn't what you are looking for but, pop the hood and have a look see.
1969, X-44, Export Model, Hugger Orange, Std. Int., BC Rear(soon to be a BT 12 bolt), PDB, GMPP 350HO, M22 Supercase, SSM Lift Bars, AirGap, Holley 750, FlowMaster American Thunder Exhaust, FlowTech Headers