73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Electrical => Topic started by: Hank Hill on January 18, 2008, 02:28:57 PM
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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 break lights.Well im pretty sure I had break lights? I must have had break lights. Yes im sure I did. Well pretty sure. Well it had to have had break lights at one time. 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
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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 scrath? Example I need two of those switches for the brake linkage but then where do I hook the wires to?
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#1 forget about your trailer until you figure out your base lighting ckt. Always go to the source. These trucks only have two brake lamp bulbs and the possibility of them both being out is there. 4 screws and you can check a bulb to see. If you have no B+ at the lamp socket when the pedal is depressed check the stop lamp switch. It's located on the brake pedal arm bracket. You can jump the switch and see if the lights come on or try adjusting the brake lamp switch. Do you have a 12V test light?
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See the stop lamp switch on the pedal linkage isnt there.
I know what happened. This truck originaly had cruise control. When the criuse control 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. 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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The brake switch wiring would have to have been cut in order to have been removed. Why would someone cut it out? Are you sure it's not there?
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The wire that hooks to your switch that goes out to your tail lights should still be there. Just hook that wire to your new switch and run costant hot wire from your fuse block to the other side of your switch and you should be back in business.
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http://cgi.ebay.com/ebaymotors/1973-1987-chevy-gmc-truck-brake-light-switch_W0QQcmdZViewItemQQcategoryZ50459QQihZ010QQitemZ200192309298QQrdZ1QQsspagenameZWDVW
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Do you have a lockup transmission?
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I replaced the TH350 when the houseing broke with a 350c lockup but there are no wires running to it.
As far as whats there for break light wires im just going to have to take that dash a part to get a better look because I cant see any cut wires from just looking up underneith the dash.
Were getting a snow storm right now so this repair is going to have to wait.
A buddy has a shop and he also has a junked GMC truck with no air and an auto transmission in it. According to parts catologs if you have air, criuse or an auto transmission you use a different brake light switches. My truck originally had air/ power doors, criuse but all of this stuff was taken off. Anyway his switch and hopefully his wire harness should hopefully fit my truck.
Anyway when my buddy gets some of his current projects done im going to take my truck over and use his shop. Will let you know how I make out. Thanks for the tips.
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Your lock up convter wire should run through your brake switch. So when you press the the brake petal the trans will down shift one gear and when you let off of the petal the trans will shift back up.
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air shouldn't matter. the only options that might matter to the brake light switch are cruise and auto/manual...
look at your wiring harness in the rear...at the taillights. one of those wires are to your brake lights...i think it's the brown one. anyhow, you can narrow it down with a multimeter...my Haynes manual is unclear but i think it's the brown one. anyway, just take your multimeter and check for voltage with your parking lights on. the other wire you should see is black...that's a ground. the "odd man out" is your brake light wire. just carefully (it's gonna be a pain) start tracing it. then you'll figure out where it "ends" or if it does at all...
ok, now, if you wanna check from the other end, look under the dash around where the brake pedal mounts. there should be two wires, one being an orange which is hot all the time (coming from the fusebox) and the other should be white (i keep saying "should be" because i don't have a factory service manual, just this Haynes POS). if you see these two wires grouped together then that is the connection. then you'll just need a brake light switch. if you still have the factory connector (they can hide on ya) the you are most likely gonna have to get the brake light switch for the options it originally had, so the connector will hook up, unless you are gonna cut and splice it.
hope this helps, good luck!
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Your lock up convter wire should run through your brake switch. So when you press the the brake petal the trans will down shift one gear and when you let off of the petal the trans will shift back up.
The brake switch will not cause it to downshift it will simply de-energize the TCC solenoid.
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Your lock up convter wire should run through your brake switch. So when you press the the brake petal the trans will down shift one gear and when you let off of the petal the trans will shift back up.
The brake switch will not cause it to downshift it will simply de-energize the TCC solenoid.
Cool
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Hey thank you all very much.
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Weither you have air or not, doesn't make a difference.... A Cruise Control switch is a two-stage switch, front half controls the Brake Lights, and the rear half controls the Cruise Disable.. When you add overdrive or a Lock-up converter to the mix, another stage is added(In some cases it can be just piggy backed off of one other halves of a two stage) to the middle of the switch....
Non Cruise, Automatic Switch
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/ACDelco/D850A.jpg)
Non Cruise, 4spd Auto/Auto wih Lock Up Converter
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/ACDelco/D851A.jpg)
3spd/4spd Auto, With Cruise
(Corrected so as to not leave Fordeatinz71 out ;D)
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/SMP/SLS-159_FULL.jpg)
Non-Cruise, with Manual Trans.
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/SMP/SLS-66_FULL.jpg)
Those are the majority of the different switches available, with a few exceptions... In some of the Older trucks with Cruise, a seperate Stop Lamp Switche was used for each feature(Ie Brakes got one, and Cruise got another).. Some Early 4spd/Lock-up Trans models, employed one two stage switch for the Cruise and Brakes, with a single stage switch pulling duty for the TCC...
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ok, now, if you wanna check from the other end, look under the dash around where the brake pedal mounts. there should be two wires, one being an orange which is hot all the time (coming from the fusebox) and the other should be white (i keep saying "should be" because i don't have a factory service manual, just this Haynes POS). if you see these two wires grouped together then that is the connection. then you'll just need a brake light switch. if you still have the factory connector (they can hide on ya) the you are most likely gonna have to get the brake light switch for the options it originally had, so the connector will hook up, unless you are gonna cut and splice it.
hope this helps, good luck!
Hey man you were exactly 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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Weither you have air or not, doesn't make a difference.... A Cruise Control switch is a two-stage switch, front half controls the Brake Lights, and the rear half controls the Cruise Disable.. When you add overdrive or a Lock-up converter to the mix, another stage is added(In some cases it can be just piggy backed off of one other halves of a two stage) to the middle of the switch....
Non Cruise, Automatic Switch
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/ACDelco/D850A.jpg)
Non Cruise, 4spd Auto/Auto wih Lock Up Converter
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/ACDelco/D851A.jpg)
3spd Auto, With Cruise
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/SMP/SLS-159_FULL.jpg)
Non-Cruise, with Manual Trans.
(http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A//info.rockauto.com/SMP/SLS-66_FULL.jpg)
Those are the majority of the different switches available, with a few exceptions... In some of the Older trucks with Cruise, a seperate Stop Lamp Switche was used for each feature(Ie Brakes got one, and Cruise got another).. Some Early 4spd/Lock-up Trans models, employed one two stage switch for the Cruise and Brakes, with a single stage switch pulling duty for the TCC...
So since my truck now has a non lock up (unhooked 350C) auto transmission and it no longer has cruise control. I guess that a 2 prong brake light switch like the one you show on the bottom for a manual, non cruise is best for me?
If I have to use one of the other brake light switches for lock up/ cruise that has extra terminals I guess I just try the different terminals until I find the right ones? Probable start with the terminals that are farthest away from the part of the switch that contacts the brake linkage?
Thank You
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Instead of calling myself Hank Hill I should call myself Homer Simpson because I was haveing a Homer moment in my last post, Duh.
A Brake light switch is just a switch so it shouldnt matter which set of terminals on which end of the switch I hook up to.
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Instead of calling myself Hank Hill I should call myself Homer Simpson because I was haveing a Homer moment in my last post, Duh.
A Brake light switch is just a switch so it shouldnt matter which set of terminals on which end of the switch I hook up to.
Actually Homer, since it is only a $9-20 switch, why not buy a new one specific to what you are trying to do, so you don't have to worry about the Old/Salvaged Switch not being wired correctly???
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glad ya got it going man. yea, one switch ya missed dragon...the one for my setup (although you mentioned it)...i have a 4 spd. auto and cruise...heck, looking in the classic industries catalog, all they wanna know is do you have an auto and do you have cruise. they don't care about lockup convertors or whatnot...but that's because they go by your year and just give you what your truck originally had...
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glad ya got it going man. yea, one switch ya missed dragon...the one for my setup (although you mentioned it)...i have a 4 spd. auto and cruise...heck, looking in the classic industries catalog, all they wanna know is do you have an auto and do you have cruise. they don't care about lockup convertors or whatnot...but that's because they go by your year and just give you what your truck originally had...
Lol Technically I did post a pic of it(second one up from bottom), I checked and had it comfirmed, GM just Piggy backed the TCC on 82/83 and Up models with Lock Up Converters/Overdrive(As I also stated in my prior post)... So the Lockup/4Spd Auto. Models just used the same switch as the 3Spd Auto. Models.. Non Cruise Lockup/4Spd Models use their own Two Stage switch, with the front controling the Brakes, and the Rear Controling the TCC. The Two Stage switch for Models with Cruise, the Forward portion of the Switch Controls the Brake Lights & TCC, with the rear Controling the Cruise.... ;)
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Not trying to hijack this thread, but I have a similar issue. My signals, hazards, and brake lights (when pedal is pressed) work, but the parking lights (in the rear, dual filament bulbs) don't. Is this a ground or what?
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Not trying to hijack this thread, but I have a similar issue. My signals, hazards, and brake lights (when pedal is pressed) work, but the parking lights (in the rear, dual filament bulbs) don't. Is this a ground or what?
Start with the ground, check the other wires as well to make sure there isn't any cracks or breaks in the harness causing a short... If all that checks out, what do the bulbs and sockets look like?? Simple things I know, but it is possible that it the bulbs have been exposed to moisture, they or their sockets could be shorting, but still allowing partial lighting to occur(In this case your Brake Lights).. I had an '80 Seville,'86 Park Avenue, and 87 Lesabre (still have a '79 Monte Carlo as well) that all had notorious sealing problems with the socket gaskets, and taillamp seals allowing moisture in that would short the bulbs/sockets... Easiest fix for them was to replace the gaskets that really need to be,replace any severly corroded sockets, clean & slightly bend the bulb tangs of the sockets that weren't replaced, then silicone sealed the rest of the lamp assemblies... Never had any problems with them afterwards, and they were much brighter then before!
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Instead of calling myself Hank Hill I should call myself Homer Simpson because I was haveing a Homer moment in my last post, Duh.
A Brake light switch is just a switch so it shouldnt matter which set of terminals on which end of the switch I hook up to.
Actually Homer, since it is only a $9-20 switch, why not buy a new one specific to what you are trying to do, so you don't have to worry about the Old/Salvaged Switch not being wired correctly???
Well im not going to buy new if I can help it because hopefully the one a get off the junked truck will have the wires /factory terminals to plug right in to my truck.
If I do end up buying new I would probable have to order it from Chevy Duty and since im in Canada that $10 part would probable end up costing me $50-$70.
I guess if I did buy new, the one for a standrd transmission and no cruise would be the one I need because its the only one with just two plugs. Thanks again for posting the pictures.
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Instead of calling myself Hank Hill I should call myself Homer Simpson because I was haveing a Homer moment in my last post, Duh.
A Brake light switch is just a switch so it shouldnt matter which set of terminals on which end of the switch I hook up to.
Actually Homer, since it is only a $9-20 switch, why not buy a new one specific to what you are trying to do, so you don't have to worry about the Old/Salvaged Switch not being wired correctly???
Well im not going to buy new if I can help it because hopefully the one a get off the junked truck will have the wires /factory terminals to plug right in to my truck.
If I do end up buying new I would probable have to order it from Chevy Duty and since im in Canada that $10 part would probable end up costing me $50-$70.
I guess if I did buy new, the one for a standrd transmission and no cruise would be the one I need because its the only one with just two plugs. Thanks again for posting the pictures.
Well Dang you got to go and make things difficult for ya, don't ya :o Didn't know your a Cousin to the North, thought you were State Side ??? Yeah I definately see your point now, hope it works for ya! No Problem with the pic, and that was more or less the idea of posting them all, so as to give you a little more to work with for your application!!! Good Luck to Ya Bro! 8)