Brake lights and horn don't work, help!

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Joelster

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As the title says neither work. I took each bulb out and wired them to a spare battery. Both bulbs work. I read somewhere that there is a circuit breaker near the glove box that controls horn and brake lights?. I removed the glove box to have a look but can't seem to locate anything. I could just rewire them but I'd rather not. Any help is appreciated!

 

jscott

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Did you check the fuse for the horn (same fuse runs the cigarette lighter)?   I have a short in my lighter that blows the fuse if I use it, making the horn inop.

 
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Fuse block is below the steering wheel and a bit*h to get. Probably a fuse and first place to look. I think there are wiring diagrams posted on here somewhere. If it was just the brake lights, I'd say look at the brake light switch. It may be f'd or just out of position.

 
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midlife

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Two separate systems.  Brake lights get power from a circuit breaker, then goes to brake switch, then to turn signal.  Circuit breaker is located on metal "Z" box where a lot of other relays and such are located. 

Horn gets power from lowest left side fuse, shared with cigarette lighter. 

 

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I got the glove box out. I think I found the relay for the brake switch. I have no power at the switch. The wires are olive green with brown stripe. I unplugged the relay and have no power at either of the plugs going into it. Is this the correct relay? Am I missing something? Battery has 12.5 volts.
 

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I’m not an expert, but those pictures look like the signal light and 4way hazard light relays.

it has been some 30 years since I replaced a brake light switch ,but it looks like this....and if I recall it correctly is attached to the brake petal under the dash (when you depress the brake petal, it engages the brake light switch to turn on brake lights)

i have no expertise to add to your horn issue.

good luck
 

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Joelster

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I bought a new brake switch for the pedal, but I'm not getting power to either lead going into the switch. One of the pics is of the brake pedal switch. The same colored wire goes into that relay so I figured it has something do with it. But neither of those wires have power either. I'm an electrical newbie and electrical problems seem to find me all of the time.
 
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Ok, I have had a problem with no brake lights before. New switch and I still didn’t have them working. Anyway long story short, the main wiring harness plug on the steering column was not making a good connection. I believe it is actually the turn signal harness. I have had it happen a couple times.
 

midlife

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That is the correct plug for turn signal flasher. Power comes from a circuit breaker with a yellow wire and a green/red wire, which routes to the turn signal switch flasher can and then on to the brake switch. If no power, either the circuit breaker is defective, or any of the two wires mentioned above are not plugged it. No fuse is involved.
 

Joelster

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Where is that circuit breaker located? You mentioned the "Z" bar in an earlier post but I have no idea what that is. I even Googled it with no luck. I did find 2 random plugs just hanging loose in the glove box and one of them had 11.5v of power when I checked it. I can't even see anything where it would plug into though.
 

midlife

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There's a metal frame with a bunch of relays, connectors, etc. somewhere behind the glove box. Those two leads are probably them. They fit into a CB mounted on a longer piece of metal. The hot wire is yellow; the brake line power is green/red.
 
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I got the glove box out. I think I found the relay for the brake switch. I have no power at the switch. The wires are olive green with brown stripe. I unplugged the relay and have no power at either of the plugs going into it. Is this the correct relay? Am I missing something? Battery has 12.5 volts.
Those are the oem flashers. There are relays and circuit breakers just above the glove box, accessible after removing the glove box liner. See the attached file for details on the Relay Bar. Some of the items are for optional features that may or may not exist on various cars.
 

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As the title says neither work. I took each bulb out and wired them to a spare battery. Both bulbs work. I read somewhere that there is a circuit breaker near the glove box that controls horn and brake lights?. I removed the glove box to have a look but can't seem to locate anything. I could just rewire them but I'd rather not. Any help is appreciated!
Here are some files that may help. I have another PDF file with a lot of turn signal circuitry info that may help. The file is too large to attach via this forum and comment. But, if you email me a request for the 1973 Turn Signal Circuit PDF file I will add your email to my DropBox.com site where you can download it from. You can reach me at [email protected]
 

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Joelster

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Thank you very much! That pic showing everything in the picture is likely all I will need! I will dig into the car a bit more this weekend and let you know how it turned out.
 
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Thank you very much! That pic showing everything in the picture is likely all I will need! I will dig into the car a bit more this weekend and let you know how it turned out.
The schematics I have include the fuse block circuitry. It is possible you have a fuse issue with the horn is not working also. These three PDF files were small enough to attach. Hopefully they will hepp you.
 

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Joelster

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Thanks to everyone for the help!

Update: I got them to work, but good news/bad news lol.

There is no circuit breaker in our car. There's a bunch of loose wires with plug ends on them. Found one that had 11+ volt and jumped that into the green/red wire at the turn signal can. I used a cotter pin to jump it. Can I just run a in-line fuse on that wire to have brake lights or does it have to be a circuit breaker?

 

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midlife

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Circuit breakers are cheap, and readily available. They are better than inline fuses, as you don't have to replace them every time you have a problem. Plus, you have no idea what's providing your power and you could overload it but not the inline fuse. Don't be a cheapskate!
 

Joelster

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I picked up a circuit breaker and a box of round fuses. I'll see if I can get some time to tinker with it this weekend.
 

Joelster

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Got the circuit breaker in. I made 2 short jumper leads to connect to the factory plugs as I didn't want the cut either plug off. Tested it real quick and it works, see pic. Then I mounted it up high out of the way and reinstalled the glove box.

Now for the horn! Pulled the fuse and yep, it was blown. Put a correct 20a fuse in and still no power at either horn wire coming out of the wheel. Checked with a voltmeter. So I took a 5' piece of wire and touched it to the 20a fuse end for the horn at the fuse box, and then touched the other end to the innermost wire on the steering wheel and the horn worked! So somewhere between the fuse box and the horn button the connection is lost. I really don't want to dig Into the column. Is there enough clearance to just rewire that 3-4 foot connection? Or do I need to use the factory setup because the wheel goes 2 turns lock to lock?
 

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Joelster

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I'm getting power to the bottom spring loaded post. Somewhere in that copper ring it's losing power. If I put the hub back on I don't get power to the outside wire. Maybe the contacts need a cleaning?
 

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