I have a 1970 cutlass supreme convertible, 350, Factory AC but not hooked up.
Yesterday I installed a new Horn Relay. Horns now work. So I close hood and call it a successful day. Today, I go out to start the car and nothing. So I raise the hood to hook up Battery charger and there is some sparking from the positive battery cable. when I grabbed the battery cable the Horn Relay sparked. I hooked everything back up, that was on it. I think??? The previous owner was a Hack. The wiring on this car is cobbled up pretty good. So after studying the the wiring diagram and the factory build sheet to see what wire went where. I don't think any thing is wrong. Also while I was installing the Horn Relay. The brass cover came off. I had to work at it pretty good to get it back on. Could that be touching something on the horn relay?

So any ideas? I did a search on here and nothing. what wires don't need to be hooked up so I can maybe eliminate the problem? I'm guessing I can leave the AC relay wire off?? I really don't want to burn the car or my house down.

 

Yes.




Or, Yes, all of the above may be correct. Or may not be.

How about we start with describing where the sparking was coming from? Which terminal or location.
Take a picture and show us. Show us the wires.

At this point almost anything is possible, because you have described the problem so vaguely.

And disconnect your battery.

- Eric

 

Battery has been disconnected already. The little sparks were coming from the positive side of the battery. The big spark came from the Horn relay itself when I basically jiggled the positive battery cable to see if it was loose,it wasn't. no particular wire. I unhooked the battery right away after that. I will go take some pictures. Trust me your going to be sick when you see this mess. I was just now looking at Super cars unlimited for wiring harness replacements it might be a better way to go.. hold tight pictures coming in a few.

 

I'd replace the horn relay first and go from there.

 

He just did replace the relay.











Okay, there are a lot of wires there. You need to figure out what goes to what, and whether any of them don't go anywhere.

Then just hook up the one(s) you need (general wiring harness, starter, maybe High blower speed) and leave the rest.

Then reconnect the horn relay and see what happens.

I must ask again, though, exactly where did the spark occur?

- Eric

 

When you jiggled the Positive Battery Cable you should not have had any sparking at the Battery Terminal unless either the connection was loose, or you possibly have a bad cable......... as mentioned, try to figure out where each wire goes to and hook up essential wires only at first. The one that goes to the bulkhead connector may give just a tiny spark if you have an electric clock. None of them should give any sort of significant spark when touched to the Horn Relay.

 

Right, and then the trouble started
New is not equal to perfect.

It is possible that the wire fiddling involved in the relay change is what fixed the horns, and the old relay was actually OK.

Sparks and no-start are not correct though.

 

Ok Thanks again guys. I fixed the problem. The last person to respond was right. I figured it out then came here to see that someone mentioned it. Yes! the positive cable was bad. Actually it was the post connector. And the cable inside it. I put a new post connector on and that solved the problem. I should have known. I have dealt with enough hacked up wiring with this car. I think though, the sparky sparky did something to my new horn relay. The door buzzer doesn't work now. It did yesterday after the first install. I will replace again next week. The horns still work which was the reason I had to change the relay to begin with.

 

If the cover came off, I figured it might have damaged the contacts and caused arcing from the internal parts to the cover.

 

Yeah me too. I will buy another one. 50.00 dollar mistake. Could have been worse.

 

But the cover shouldn't have damaged anything coming off.

In fact, it shouldn't have come off at all.

How, exactly, did you make it come off?

If you could take it off again, you could look at the parts inside and confirm whether everything's in good shape or not.

- Eric

 

Had to say but maybe one of those disconnected wires are hot and touched ground when wiggling things.

 

Keep in mind that a small spark may be normal upon connection of the main line going to the fuse block, or to an amp or such.
Radios, alarm units, tachs, and other electronics have filter capacitors inside that discharge when power is disconnected. When reconnected, all of those capacitors charge up at once (and act like a short until they are all charged, taking a second or two). This will result in a nice little spark the first time it is reconnected.
If you take it off and reconnect it within a few seconds, there may be a tiny, or no spark.
Now if each time there is a large spark, or wires get warm or hot, then there is another issue.

 

I had the Relay in my right hand. wrench in my left. When I pushed down on wrench to tighten nut on the Hot lug the cover just popped off in my hand. This is an Autozone part, so it may not be the best of quality.

 

I'm Aware of small spark. This was a Huge! spark. I posted a few post up the problem has been solved Changed Battery post connector. plus fixed some exposed wiring near the post connector.

 

The wires were all connected at time of spark. I disconnected them after spark and to take picture.

 

I wouldn't worry about it, then.

- Eric

 

I could barely see in one of your pictures that your positive cable has one of those temporary battery terminals on it. I hate seeing those under the hood, they don't look good and sooner or later there will be connection problems where the cable clamps on to the terminal, spend a few extra bucks and get a complete cable....

 

Take the neg cable off and put a test light in between and see if there is a draw to be safe!