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Discussion Starter #1
It was on my firewall of my 72 El Co. It had the purple wire and 2 other wires form my starter on it.I checked the local parts store and nothing...

 

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Looks like a horn relay to me. Was it just above/behind the brake booster? The threaded stud is where all the +12v supply wires come together. having the purple wire from the starter on it sounds odd, not sure what to make of that.
 

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Discussion Starter #3
Yes, its right behind the brake booster. This is what happened, i ground out the alt. stud on accident and the starter started smoking.I pulled the starter and the fusable link was smoked too, i cut it out and reconnected the wires and now i have no electricity to the car AT ALL. I used a test light following the purple wire and it went to the stud in the picture. Than from the stud it goes into the fusebox. I took off the fuse block from both sides and checked it and it looks ok. I assuming this relay has something to do with why its not starting.

Thanks for the Help
 

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I just put a new horn relay on my 70 and it didnt look like that.It was mounted on the rad saddle next to the rad!
Gerry....
 

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Discussion Starter #6
On my old 1970 it was by the Rad. also but i think on 71-72 they are behind the booster but not 100% sure.
 

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That relay is used only on the 72 Chevelle. It doesn't need to be fuctional to start the car. However, it or a terminal block is needed to connect wires.
Purple wire from the starter "S" terminal does not go to this terminal. Only the large wire from starter B+ (the one with the link).
I'd put everything back together and measure the horn relay large terminal to ground for 12 volts as a first step.
 

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Discussion Starter #9
replaced the relay and nothing, some reason the headlight sockets got juice but no head lights. I wonder if its the hreadlight switch or high/low switch. as soon as i turn the key on i lose all power to car. If i take + cable off and wait a few secs. it might come back on. Strangest thing ive ever seen.
 

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When the key is turned on, do you have 12 volts on the large terminal of the relay? If you do turn on the headlights and measure that point again.
 

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It seem to me that you have a faulty ground connection somewhereor are missing a fuse link somewhere. keep in mind there is a fuseable link in the harness near the bulkhead connector as well. I believe it feeds the ignition switch. My chevelle wiring book has the info in it. If you dont have a manuall try the library. They have a whole section of repair manuals. I will check this post when I get home from the office tonight. If you have no luck, I will jump back on.

Milan
 

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Discussion Starter #12
YES, got juice to the relay and past it with a test light. Whats strange is the headlight socket have juice but when I turn on the headlights they dont come on...The left side of fuse panel has juice but right side has none and when i turn the key on its all lost. to me it sounds like a ground problem...solid motor mounts, new ground strap from battery to block, so still working on this problem.
 

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Does voltage drop on the fuseblock BAT terminal when you turn on the key and turn on the headlights at the same time?
 

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Body to engine ground? Body to frame ground?
The voltage at headlights is probably backfeeding. as John posts you need a meter and measure the voltage.The term juice makes my skin crawl. If you have the correct voltage at the proper terminal at the head lights and they are grounded as they should be, they would be on.

Milan
 

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Originally posted by Milan:
Body to engine ground? Body to frame ground?
The voltage at headlights is probably backfeeding. as John posts you need a meter and measure the voltage.The term juice makes my skin crawl. If you have the correct voltage at the proper terminal at the head lights and they are grounded as they should be, they would be on.

Milan
I know you will understand. I'm guessing there's voltage but no current. That's why I asked for the measurments with the circuit loaded down.
Originally the alternator line was shorted taking out the main fusible link down by the starter. That link controls the whole car in 72. If that line wasn't properly repaired, the car will have issues.
 

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John You are definately on to something. I didn't have the time last night to look this up. I believe there is a power take off point that has an additional fuse link on the firewall somewhere around the wiper motor/master cyl area. I believe that wire feeds the ignition switch inside the car. I was leaning toward that fuse being faulty as a result of the short. He may very well have two problems as the headlight issue was there when he purchased the car,no?

Milan
 

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You are correct on the additional link. However, it doesn't feed the ignition. It feeds the left side or the BAT side of the fuseblock. That side of the block goes on to feed non-switched items, brakes, ignition switch input, headlights...
Still haven't heard if there is 12 volts on either the horn relay terminal or the BAT terminal when the circuit is loaded down by turning the key to ON and the headlights pulled ON.
How's this sound. This should load the line.
Unplug the horn wire from the relay. Believe it's a large green wire. Touch that to the relay stud terminal. The horn should honk.
 

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I learned something new today


Milan
 

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Originally posted by Milan:
I learned something new today


Milan
Well, in the end you might be right about that link. However, it shouldn't have gone out when the alternator was shorted. Wasn't in the path to ground and if it took off it should have smoked. Unless it was open in the first place, it shouldn't be a problem. Checking the fused BAT terminal will also check that link.
The link down by the starter is a pain to change. Not done properly and things act a little funny.
 
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