I inherited a 1980 Corvette with 70,000 miles on it from my father because he's getting dementia and doesn't drive these days. He bought it in 1994, took some great pictures of me in it back when I was a kid, always kept it in a garage, took decent care of it, but it has a number of wonky things going on with it. The most pressing issue today is electrical.

I went to a convenience store. When I put it in park, the radio seemed like it went on mute for a few seconds. I think the power remained on and I turned the car off. When I returned from the store a few minutes later, I went to start the car and when I turned the ignition key, it didn't crank and I noticed that nothing electrical related was functioning. I walked home and got my multimeter. The battery was at 12+ volts. I pulled all of the (rectangle shaped) fuses and tested them for continuity, none seemed blown. Under the hood there was what appeared to be a ground wire that wasn't connected to anything. It's located on the passenger side about a foot in from the windshield just dangling. I didn't do anything with it, closed the hood, got back in the car, and turned the key and the car had power.

I returned home, turned the car off, tried to turn it back on and again, no power to anything. Disconnected the battery via the switch, ate dinner.
When I returned, I reconnected the battery, put the key in the on position, started pulling fuses again, still looks like none are bad. I sat in the drivers seat and started texting friends about what a shitty week this is (my brother died this week, I'm using the car and this post to keep me busy), and the car just randomly got power, all accessory lights, aftermarket cd player (probably from 1999), and dash lights came on. I turned the ignition and it started right up.

WTF!


notes:
- I washed it today. My old man always said it leaked like a screen door on a submarine. I got new t-tops this week but I can see how water might leak down into the space between the doors.
- Irrelevant but I changed the oil two days ago.
- My father said there is a slow battery drain. There's an electric disconnect slider next to the battery, when not driving I've been switching the power off.
- Based on the records in the glove box, my father has replaced the battery a number of times over the years and took it into the shop for draining battery.
- The horn doesn't work, hasn't worked for years. I read in other threads that power comes from the battery to the starter, thru a large red wire to the horn relay, to the firewall connector, then the fuse panel. This doesn't make sense to me but because of this info I think it's worth mentioning that the horn doesn't work...

 

Buy a copy of the dealers service manual for an 80 corvette. Worth its weight in gold.

 

The first place I would look is the connections down by the starter. If you are having moments with zero power and then everything is fine, you have a short down by the starter where the positive cable ties into the rest of the system. Also corvettes need their grounds. Because it's fiberglass it doesn't conduct electricity, the car has several ground.

 

Sorry to hear about your brother, I worry about mine all the time.

The negative battery cable grounds to the chassis frame. The connection is on the drivers side, more or less lining up with the end of the door. If you can jack up the car, remove and clean that connection, it will eliminate one source of this problem. Also check the condition of that cable end.

 

Here is a free copy of the 1980 Corvette electrical trouble shooting manual.
1980 Corvette Wire Harness Trouble Shooting Manual Schematic

If you have a parasitic drain, one easy way to locate the circuit it's on is to place a multimeter between the battery ground cable and the battery.... then pull fuses until the drain goes away. Once you isolate the circuit the fun begins. You can do this with a test light as well, but I like to use the multi-meter.



1980 Corvette Wire Harness Trouble Shooting Manual Schematic

 

Sounds like You have at least two separate Electrical issues. As said above You need to have a look under the Car and remove and Clean both the Grounds and the Positive Cables. The Battery drain is most likely the after market stereo and or the Courtesy Light Timer. Use the method above or a test light and start pulling fuses. The Courtesy is a very likely one and if so I would go straight to the Timer. The Timer is easy to get to remove the inside of the glove box and its an orange colored box on the right side.

 

And if it is the delay module.... I make a replacement board

Willcox

 

Thanks for all of the tips, I'm going to take the info you guys provided and dig into this during the week.

 

I have been chasing the same problem. I just ordered one of Your replacement Boards Friday. Thanx...

 

I replaced that board also due to a drain issue. That was awhile ago and boards keeps going fine.

 

Sounds like you may also have a bad starter motor or neutral switch also. My car starts perfect when cold but after driving and stopping you cant start it again until it cools.. need to replace the starter and make sure it has a heat shield on it, mine didnt so i made one.

The neutral switch.. try pushing the auto level all the way to the top and then start, or the other end of Park (there is a bit of play before you actually change gears)..

 

Received the new board today. Problem solved. Thank You.

 

I had the battery drain issue due to the original courtesy timer being bad, the Willcox board FIXED that issue in about 5 minutes. I still have a small drain somewhere as it'll drain after about 2 wks of sitting. However, not like it was (could drain it in a couple hours).

Horn wise, pull off the cap and check and see if you have the little plunger deal under the horn button and if the contacts are in there and working correctly. Bubba zip tied my metal contacts together because the little plastic pieces to hold it all together broke off at some point. Then because the horn would never stop sounding, he took the little metal plunger w/ spring out. Bought a new kit a few months ago and voila... I have a horn (didn't have one for the entire time I've owned the car...12 years).

 

My board was the issue? Please elaborate and I'll see if I can help you!

The circuit board for the delay timer can't cause a drain unless it's shorted and unless you have spiked power coning in on the ground side of the circuit you can't really blow up the board because the power side is fused and will blow. For there to be a draw on the courtesy lamp timer there has to be a short or broken wire somewhere.

 

Let me edit my orig. comment. Been a heck of a crappy couple weeks and obviously I typed that in wrong somehow. Your board was what FIXED my issue.

However, now you're bringing up something I didn't think of. If there was a draw on the original timer not your board, would it do the same thing? Literally I threw in your board and haven't had an issue. It was like all the stars aligned after that went in quite honestly. My drain problems are close to 0 (takes me about 2 weeks to get low bat now vs. a few hours). Have a drain somewhere still, but not sure it's worth going nuts over something that takes a few weeks to draw down power.

 

Have you checked the easiest basics-cleaning battery terminals and all connections/curcuits on your cut off switch? Other advice is good too, and sorry if I missed it if you have already done this