My 86 Vette has an intermittent electrical problem that even a seasoned GM mechanic is scratching his head about.

The problem is I can drive the car for days with no problems, and then one day I park it in my garage, go to start it the next morning, and it is stone-cold dead. And I mean dead, with not even enough power to turn on the under hood courtesy lights.

I have tried three new batteries in the vehicle along with the original but very well operating alternator so those two issues can be ruled out. As mentioned a very well experienced GM mechanic checked the vehicle for three days and all the time the usual very mimimal electrical draw was registering, so he never experienced the problem I am facing.

Any help/guidance/suggestions are greatly appreciated.

Thanks, Jeffrey

 

Does this happen after the car has been washed or rained on?

 

My car had an internal short in the Bose radio that did the same thing to the car. Make sure the alternator is charging and all connections are clean and tight.

 

Has your "mechanic" done a current draw check on the battery?? It should not be greater than 50 milliamps, and in most cases is less.. Some radios have given this problem in the past. When running what voltage do you show?

 

Pull all fuses that have nothing to do with running the car. If the problem goes away, add half of them back. If problem reappears it's one of the circuits you just restored if not it's one of the ones you haven't added back yet.

Work them one at a time and see which circuit is causing grief.

Add "pie" to your next poll.

 

This sounds like it could take a month and you still wouldn't know exactly whats causing it because there is usually more than one thing on a curcuit. Theres got to be an easier way, no?

 

Almost needs a baby sitter, a dc clamp-on ammeter, and a volt meter. The ammeter to check current draw and a volt meter to check for dropping voltage..

 

The suspense is gonna kill me, pull the radio fuse and see if the car is dead in the morning, I have a grudge against those dam radios and I've seen them do this crap to other cars besides mine. are you sure it isn't one of the hood lights staying on, sometimes those mercury switches crap out too.

 

I had a similar problem with my 1986 once. It happened when the car was wet, after washing or rain. Turn out the seal at the back of the distributor that protects the wires there was allowing water to get in. When the car was dry it was fine but once it was wet then that caused problems.

Another reason was below the batter is a wire loom that was dragging on the steering column. Once wet the water grounded a thin blue wire.

 

I had a similar situation on mine but it turned out to be easy one to isolate, although I still have not truly fixed it. I had my ’86 for about six months and I only drive it in nice weather (which is far and few between in CT) so it sits for days on end. I would go to drive it on a nice fall day and it would be dead, dead, dead. I’d throw on a quick charge and drive for a day or two with no problems. One day I ventured into the garage and heard a fan running…. It was the HVAC fan for the cockpit….What the hell???? It had a mind of its own. I found it running on 90 deg. days and 50 deg. nights and everything in between. It did not matter how I left the heater-A/C or fan when I shut it off. On, off, auto…. It would just come on when it felt like it and run. I just started raising the hood and disconnecting the fan if it was sitting for more than eight hours. The problem has fixed itself and the only thing I did was put in a nice, new battery over Christmas (my gift to myself). I have to wonder if the low voltage of the old battery caused some HVAC logic circuit or sensor to malfunction and lose its mind and put the battery out of its misery. I swear, the problem is now gone with the new battery. Anybody ever hear of this???

 

Thanks to all for the replys. I am away for a month right now but when I return I will be investigating all suggestions. I experienced this problem in dry weather so believe I can rule out the possibility of wet weather. The radio short wouldn't surprise me nor the fan functioning on and off.

Thanks again,
Jeffrey

 

Check to see if your courtesy lights are going out after the delay runs out. Sometimes the courtesy light switches in the doors get sticky and don't turn out the lights. It's easy to overlook this because you're used to the lights staying on as you exit the car and don't realize that they're still on hours later while you're watching TV...

 

My 86 vette has same problem, I spent 1000 dollars to have wiring checked for short, no good results, I use a battery tender, If u figure it out, let me know