The other day, I started the 68 vette to show a friend. it started and everything worked fine, no problem until I turned on the wipers. The door opened but then the wipers didn't activate. I thought great, I spend hours getting all the wiring and the vacuum hoses working about 2 years ago and now it dosen't work again. I didn't have time to work on it then, so I just shut it off and left it as is. Two days later, I went out ot start it and it was totally dead!. Thining maybe the wiper motor might have stayed on and drained the battery, I turned the **** on the disconnect switch I added between the battery and the positive battery cable, and connected a battery charger to the battery. After two more days, I jumped in, reached around to tightnen the **** on the battery disconnect switch. I tried the key and there was nothing. That's when i noticed the smoke coming up from under the hood! Lots of smoke, the burning electrical smelling kind of smoke! I reached around behind me and unscrewed the ****, which then fell off in my hand, the battery coble didn't disconnect and the smoke continued. I reached back to try ti wiggle the cable off and just burned my hand. I jumper out and grabbed apliers and wrenched to negative cable clamp off the battery. The whole garage was filled with smoke! After the smoke cleared a bit, I opened the hood. The red insulation on (#10?) wire from the starting solenoid to the horn relay was totally burnt off along with the wiring harness it was in and damage to adjacent wires. I know that the bracket on the horn relay is a common distribution point for +12 volts, but none of the other wires leading away from the horn relay bracket were burned. I assumed the horn relay bracket must have gone to ground some how. I disconnected all the wires at that horn relay bracket and it wasn't grounded, so the short must be downstream of the horn relay bracket, but why isn't one of those other wires burned too! Sorry for the long post, I guess reliving the near loss of my baby got the adreniline flowing again. Could this have something to do with the wiper motor incident four days earlier? DonO

 

The starter solenoid end of that #10 red wire should have a fusible link on it,sounds like someone might have eliminated it.

I think once you report back about the fusible link we can try to put together a chain of events as to how this happened and why but because the #10 burned into other wires it will be mostly guessing , bottom line you've got some work ahead of you.
Then you have to make sure it doesn't repeat itself.
68s do have a history of the wiper wiring causing issues.

 

Roger, you are right about the fusible link right at the solenoid, I'm guessing that it might have been eliminated some point along the way. I got the AIM manual and a good wiring diagram, so i'll tear into it this weekend and reprt back to the forum on what i find. There is a picture posted on the bulletin board at Corvette Specialty, our local corvette store here in Minneapolis, that shows a beautifilly restored maroon 68 vette and the "after" picture of what was left when the electrical system shorted and caught fire while he was driving thru a local college campus. There wasn't much left that was recognizable. I definitely agree with you that I need to find the root cause and make sure all the fusible links are in place! Thanks for the response.

 

I did something similar on mine. I grounded a wrench out under the dash with the battery still connected.

Even though I have 2 fire extinguishers in the garage, as well as wrenches, I was surprised at how fast the situation turned serious. The fumes were instantly toxic to my eyes, and lungs, and I couldn't touch anything without burning my hands.

Needless to say, I now see how important that fusable link is.

good luck

 

Boy, you are right about the toxic smoke! I was gagging and almost threw up after just what was probably just a minute or so of breathing that stuff. I'm going to replace the battery cut off switch from the **** type to the knife switch type, which should be more positive in a panic situation.

 

Roger,

I was able to work on the covette for part of the weekend. I tried to do some troubleshooting with my analog meter, but first had to isolate the red wire (from the solenoid to the horn relay) because it was essentially burned bare and was grounding out in several places. What I found out is this, there seems to be two shorts or paths to ground, I had about 3 ohms to ground on the red wire to the wiper motor and the #10 red wire to the alternator had a low rsistance to ground. I didn't note what that resistance value was, and later when I tried to repeat the test, with two different meters, it read infinity. But there is evidence of that red wire overheating and melting the wiring harness near the alternator.
So right now my plan is to replace the wiper motoer and the alternator.
The wiring harness did have a fusible link in it, but it sure didn'y fuse open.
I'm thinking about adding a 30 amp in line fuse that I have to believe would open quicker that the fusible link.
I also noticed that the ammeter in the dash is now permanently pegged over to discharge. I guess I'll need to tear the console apart and fixt that too. Soooo, so far I'm looking at a wiring harness, wiper moter, alternator and an ammeter! Yep, this is turning into quite the project. Any other suggestions while i got everything torn apart?

 

OK, can anyone tell me why the three pictures didn't come in, I copied the URL from photobucket for those pics????

 

You didn't insert them with UBB tags.

 

Great, Thank you very much!!!

 

This may sound crazy, but I'm a convert and have been doing this now for quite some time with great results.

Here are the long, gory details.

A couple of decades ago, I had a tricked out Econoline Van. One day, I went in to start her up and smoke and melted wires dominated the scene.

It was awful. Just like your vette.

A fuseable link had failed, or didn't work properly, or something. Anyways, I replaced all the wires and put in a new fuseable link.

Now, you know what is coming. YES, I went to start it, and Poof, the link went and the wires went up in smoke again.

I had to figure out a way to test this and track down the problem. It just so happens that not only am a I vette owner, but I have Harleys as well.

The 1977 Shovel head series Harley has three circuit breakers. Two 15 amp and one 30 amp. They are little cans with posts on either end to attach wires. The 30 amp did not exist prior to 77.

http://www.amazon.com/gp/product/B00...d_i=B007KPVW0U

Anyway, I happened to have a couple extra and wired the 30 amp in place of the fuseable link on my Van.

The circuit breaker kicks, but then will reset itself after it cools in a minute or so. It gives you the opportunity to trouble shoot and repair things without burning everything up. I keep a couple around the shop at all times.

I have since replaced many fuseable links with these little circuit breakers. You can even get the little brackets that pop rivit anywhere to hold them.

 

Ooooo thats nasty Are you sure there was a fusible link at the starter ?What wire size is it ? Did any of the fusible links at the horn relay burn ? Have you looked inside the car at the red #10s ?

 

I installed this after my incident.


I was a little worried 30 amps may not be enough, but I've driven it a good bit and no problems. All my electrics, including 2 cooling fans, come off it fine.

 

The fusible links are located in areas that have high current draw AND are connected to components that could fail internally via a dead-short, such as the starter solenoid, wiper motor, horn relay, etc. There were no fuses/circuit breakers in those locations because they should NEVER fail and fuses cost more than the fusible links. But, when there is a failure...or a dead-short due to insulation wear-thru on a high current wire [which is what I suspect happened to you], the fusible link prevents a wiring insulation fire which can quickly escalate into a vehicle fire.

Your wiper motor might still be suspect, but I think it was giving you problems because the battery was low from the [starter solenoid] wiring insulation erosion.

To be safe, you really need to reinstall the fusible links, wherever they have been removed. From one of your photos, it can be seen that someone had replaced that fuseible link with standard wire and crimp-type butt connectors. You are very fortunate that the car didn't go up in flames.

P.S. The wiring insulation on a [properly made] fusible link will char, but won't burn prior to the [smaller] internal wire melting and breaking the circuit.

 

Guys

Is there a comparison list that could be consulted to say what the fusible links were designed to handle as far as current so that a proper sized fuse and type of fuse could be used instead?

Would a 30 amp slo-blow be need for example or is 30 amps too small in this scenario since I have seen many cars with dual fusible links in parallel to the same wire?

Did some more looking on fusible links... you need to protect wiring using fusible links with a gauge 2 sizes smaller. So if you are protecting 10 gauge you need to use 14 gauge fusible link and it should not be much over 6 inches long and needs to be in open air NOT in conduit or harness tape.

 

I finally got the new wiring harness from LectricLimited, it looks really good! comparing it to the old wiring harness it's clear that someone had done some modifications at some point in time. Decided to replace the harness, alternator, wiper motor and the ammeter. When I took it apart, the ammeter was a melted ball inside!

Thnaks everyone for the help and advice. I'll post again when she's back on the road!

 

Good to hear. If you hadn't posted that, I would have suggested you replace the harnesses. The harness is garbage if it's old enough the wire insulation is getting brittle. It's even more garbage when a bunch of the wires have melted or have been hacked-up by a previous owner. You have to really know what you are doing and have the proper soldering gun, solder, heatshrink and extra wires to fix damaged harnesses correctly. Often, you need various new connectors and some of the high temp insulation wire to use for new fusible links too. And that is after assessing the current wiring and knowing it's in good shape everywhere else.