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Old 01-20-2008, 07:47 AM   #1
Roper
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Brake lights on a 81 GMC

All lights/signals work on my truck except fot the brake lights.Also the brake lights on my trailer dont work now either. Truck is a 81 GMC. All fuses seem to be working on the fuse box although there are circut breakers there that I didnt check. Have no idea when the brake lights stopped working.
Have not checked the bulbs because I cant see all the bulbs being blown at the same time.
Backup lights work to.
How do brake lights work? On the brake pedal I cant find any electrical conections that would engage them. Cant find any fuse marked brake lights.
On my 87 when you press the brake pedal it moves away fom two electrical connections(breaks the circut?) but on my 81 there are no connections. There is the bracket there for two connections(switches) but no wires or switches like on my other truck?
Here is the thing though. I have had this truck forever. I used to have brake lights.Well im pretty sure I had brake lights. I must have had brake lights. Yes im sure I did.Anyway I didnt remove the switches or wiring so they must not have ever been there? Right? Im totally confused. So do the break lights work differently on a 87 than they do on an 81?
Any ideas about how I could fix them? Thanks
PS
Man I looked everything over and that truck must have been without brake lights since I had it. The factory switches that disconect when you press the brake pedal are gone, a long with all the wireing.
So I guess my question is now how do I wire up brake lights from scratch? Example I need two of those switches for the brake linkage but then where do I hook the wires to?
Its winter here in Alberta. Im working outside. The wireing is different on the 87compared to the 81 and I dont want to tear the 87 a part to try to figgure out how to wire the 81 if I can help it.
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Old 01-20-2008, 08:01 AM   #2
BLE 'BURBAN
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Re: Brake lights on a 81 GMC

There is a brake light switch mounted to a bracket in front of the brake pedal arm.
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Old 01-20-2008, 08:09 AM   #3
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Re: Brake lights on a 81 GMC

There is a bracket there but no switch and no wires. I know what your talking about but there not there. Only the bracket.
I looked everywhere because I figgured the switch or atleast some disconected wires would be under the dash somewhere but I sure cant find them.
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Old 01-20-2008, 09:53 AM   #4
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Re: Brake lights on a 81 GMC

I know what happened now. This truck originaly had cruise control. When the criuse ontrol was removed so was the brake light switch/wireing.
One switch on the brake pedal was for the cruise and the other one was for the brakes. LMC shows the switches for the brake lights are different depending on if the truck had cruise control. Guess I now need a switch for a truck with an auto transmission and no cruise control. But how do I wire it?
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Old 01-20-2008, 10:47 AM   #5
BLE 'BURBAN
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Re: Brake lights on a 81 GMC

I'll see if I can still access a secured website when I get home to download a wiring schematic of your truck and email it to you.


UPDATE; I can no longer access the websight like I was hoping I could. There should be an electrical plug hanging under there that will plug into the brake light switch. Provided it wasn't cut off my some pucker-knutt that didn't know any better when they removed the cruise control set up. If all you find are 2 wires that WERE cut then tie them together for a moment and check to see if your brake lights are now on. If so, then all you have to do is attach 2 female spade terminals to the wires and hook them up to the switch.
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Last edited by BLE 'BURBAN; 01-20-2008 at 12:42 PM.
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Old 01-21-2008, 06:12 AM   #6
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Re: Brake lights on a 81 GMC

Were getting a snow storm right now so this repair is going to have to wait until things get a bit nicer outside.
Been a while since I had the dash a part but if I remember right there are factory wire terminals under there that are wrapped with electrical tape and not plugged into anything. However this truck originally had power doors and now it has manual so some of those plug ins are for the doors.
Well when the weather gets better im going to take the dash off so I can see better and hopefully find some wire terminals that are disconnected and join them together like you said and hopefully that will tell me if they are the right wires. Right now from looking under the dash I cant find any wires that are not connected to anything.
Hopefully I will find them with the dash off and they will be resonible close to the brake linkage so it will be obvious.
Thanks!
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Old 01-21-2008, 10:51 AM   #7
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Re: Brake lights on a 81 GMC

The plug should be white in color and have a black and an orange wire going into it. I'll see if I can get a picture of mine without freezing my nuts off. It's -26*C out there right now, so please excuse my reluctance to go play!!
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Last edited by Mickey_D; 01-21-2008 at 10:51 AM.
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Old 01-21-2008, 12:50 PM   #8
BLE 'BURBAN
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Re: Brake lights on a 81 GMC

Quote:
Originally Posted by Mickey_D View Post
The plug should be white in color and have a black and an orange wire going into it. I'll see if I can get a picture of mine without freezing my nuts off. It's -26*C out there right now, so please excuse my reluctance to go play!!
dude, you need to move to a warmer climate like ALASKA!!! It's been in the mid 20's all week here
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1990 chevy suburban V2500 5.7L
My cluster Mods-Nov 2007
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Old 01-22-2008, 11:57 PM   #9
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Re: Brake lights on a 81 GMC

Quote:
Originally Posted by Mickey_D View Post
The plug should be white in color and have a black and an orange wire going into it. I'll see if I can get a picture of mine without freezing my nuts off. It's -26*C out there right now, so please excuse my reluctance to go play!!
Het thanks for the help but man dont go out there if its that cold. Its -20*C here and im not going near my truck.
Thanks everybody. Im pretty sure I can get this working.
I was kind of worried because wireing isnt something I know much about and I know sometimes on trailers you will have oh I forget now but for some things on my one trailer the wireing gets complicated because you will have say two wires live wires and one ground that do two separate functions but if the one live wire is disconected then neither of the functions will work.
Im betting that plug is still in the dash somewhere and if it isnt then its just a matter of hooking up to the fuse panel on one end to my new switch and from there finding the brake light wire in the factory harness that goes back to my tail lights.
Thanks again everybody
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Old 01-24-2008, 04:26 AM   #10
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Re: Brake lights on a 81 GMC

You guys were right. I found about 7 groups of wires connected to un plugged plug ins all right in the same general area above the brake pedal linkage. But one only had two wires. An orange hot wire and a white ground. When I crossed the connections I had brake lights! Now all I need to do is to get another brake light switch from my buddies junked truck.
This forum is great! You know the shop rate in town is $100 hourly. I bet this saved me $200. Plus I kind of like learning about this stuff.
Thanks again!
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Old 01-24-2008, 08:22 AM   #11
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Re: Brake lights on a 81 GMC

Good to hear!!!
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1955 Willys CJ-5 all original and the oldest CJ-5 on the road.
2001 Dodge Neon (wife's car)
1995 Jeep Grand Cherokee Limited Edition SOLD
1981 K15 Custom Deluxe 4X4, rusty but trusty wood hauler. SOLD
1993 S-10 4X4 Tahoe SOLD

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