Electrical Problems

[JohnAIC]

I have two electrical problems with my 1989 Avanti 11. I have a slight drain on the battery and can't seem to find it. Also I pulled the dash and replaced the air conditioning cross over swith and have somehow disconnected my dash lights. Anyone know where I can get a wiring diagram?

[Gunslinger]

Are you sure you didn't simply blow a fuse to the dash lights when the work was done? Check the obvious before tearing things apart looking for the problem.

For the electrical drain, you can isolate the circuit causing the problem. You'll need a second person (or very long test wire leads). Remove the negative battery cable and run a test light between the battery post and the cable end. It should light up if there is a drain. Then make sure the doors are closed and all accesories are turned off and pull one fuse at a time. When the test light goes out you've found the circuit that's causing a problem. From there you can start isolating the exact problem. It's better to use an ammeter/ohmmeter tester, but I don't know what values you would be looking for as excessive since all cars will have some minute drain, particularly if they have lots of electronics on board.

I don't know if Avanti's are like this, but the electrical switches in Corvettes are different from most cars. Since the cars are fiberglass as well, switches such as the door and glovebox switches aren't self grounding. The switches are wired so they're always hot and ground when the door or glovebox is opened, completing the circuit. If Avanti's are the same way, a switch such as this could be the culprit.

[Ernie]

Do you have the factory alarm on your Avanti? I finally took my alarm off, and the battery drain is gone!

I had several mechanics try and locate the battery drain, and couldn't. That alarm was a Caffaro Better Idea!

Also, I do have a complete wiring diagram for the 1989. It has many zeroxed pages and isn't the best in the world.

[WayneC]

Good advice from Gunslinger on troubleshooting an electrical drain. One thing I might add is that all electrical components are not fused, so if you remove the fuses and don't find a drain, and the test light is still lit up with all the fuses removed... disconnect the alarm, then if the drain is still present, disconnect the alternator; bad alternator diodes can allow a drain.

Also, have a good look around the vehicle in the dark, looking for things like a glovebox light that remains on,

and /or, remove bulbs from the trunk light, underhood light, glovebox light, etc.

And, look for things that aren't working properly.... maybe one of the wires to that device is the culprit.

I had an intermittant drain issue with one of my cars that lasted a couple of years and I couldn't find it, and soon tired of shelling out big bucks to electrical shops that blamed one thing or another, disconnected the cigar lighter and completely removed the alarm system on my various visits, but never resolved the problem (I finally installed a battery cutoff switch to survive and stop the $$$ drain). It turned out to be a wire underneath the car (I think it was a backup light power wire) that had frayed insulation from rubbing/grounding against a frame crossmember... that frayed wire was inadvertently discovered by a mechanic one time when the car was up on the rack for other service. Unfortunately, some problems are tough to find.

[IndyJimW]

I have two electrical problems with my 1989 Avanti 11. I have a slight drain on the battery and can't seem to find it. Also I pulled the dash and replaced the air conditioning cross over swith and have somehow disconnected my dash lights. Anyone know where I can get a wiring diagram?

The best place to start is with the Chevrolet diagram for your chassis. My '87 uses a Monte Carlo chassis so any good repair manual would give you a diagram to start. Once you get to the firewall all bets are off, the '87 Avanti diagram manual I have can get me into the ballpark about how the factory was suppose to wire my car, but that's about it.

I would use an amp meter able to read 1/1000ths of an amp, with modern cars carrying so many electrical devices its hard on the battery. Some of the fleet vehicles I see have phones, GPS, laptop mounts and security systems. Alot of them need to be jump started after a long weekend.

Jim Wood