Brake Light Switch Issue
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Brake Light Switch Issue
I have an issue with the stop lamp switch on a 1982 F-250. I noticed that the brake lights were not working unless I was basically standing on the brake pedal. I took a look at the switch on the brake pedal arm and it was angled with the back of it pointing upward. I pulled it down. It then worked normally for about three or four sessions of hitting the brake pedal, but it eventually worked its way to the previously position again. So now I am basically adjusting the switch by hand before I go anywhere and halfway through my trip, the brake lights stop working correctly. I'm not very familiar with how this part is supposed to adjust itself. Should I just get a new brake switch and replace just that or is there something else going on here (ie.. brake switch spacers, bushings)?
Post Fiend
Joined: Dec 2007
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From: Lost
Those switches are cheap, and a lousy design. I'd try replacing it to see if that will stop it from moving up on it's own, likely caused from worn internals.
If a new switch acts the same way, it could be from wear on the rod end where it contacts the switch.
If a new switch acts the same way, it could be from wear on the rod end where it contacts the switch.
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
2 of the bushings (2B129 - C5DZ-2B129-B) are the same, 1 located on either side of the switch. The other bushing (2474 - C9AZ-2474-A) fits into the master cylinder rod.
A clevis pin (380699-S) fits into a hole on the stud, retains the whole enchilada in place. The bushings crack apart/disintegrate, the switch wobbles on the stud.
Bushings used on myriad 1965/90's vehicles and are available from Ford.
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From: Virginia
It's a weird design, you need to study it awhile and make sure it's installed correctly. To get you started, I will give you a little blurb on how it works;
First off the switch is not mounted to anything solid. It floats back and forth with the brake pedal arm. So make sure the wiring has play, these wires move back and forth each time the pedal is depressed.
Second, it's a little confusing how the switch is installed. It pretty much takes two hands, and you are all twisted under the dash already. But the switch needs to surround the arm coming from the brake booster, but also needs to slide onto the pin on the pedal arm.
If you study the situation a little bit, you will find that hole in the brake booster rod is very large, too large actually by design. As you press the brake pedal, the pin in the pedal arm takes up the slop in the booster rod. This "slop" is what activates the brake switch.
First off the switch is not mounted to anything solid. It floats back and forth with the brake pedal arm. So make sure the wiring has play, these wires move back and forth each time the pedal is depressed.
Second, it's a little confusing how the switch is installed. It pretty much takes two hands, and you are all twisted under the dash already. But the switch needs to surround the arm coming from the brake booster, but also needs to slide onto the pin on the pedal arm.
If you study the situation a little bit, you will find that hole in the brake booster rod is very large, too large actually by design. As you press the brake pedal, the pin in the pedal arm takes up the slop in the booster rod. This "slop" is what activates the brake switch.
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
It's a weird design, you need to study it awhile and make sure it's installed correctly. To get you started, I will give you a little blurb on how it works;
First off the switch is not mounted to anything solid. It floats back and forth with the brake pedal arm. So make sure the wiring has play, these wires move back and forth each time the pedal is depressed.
Second, it's a little confusing how the switch is installed. It pretty much takes two hands, and you are all twisted under the dash already. But the switch needs to surround the arm coming from the brake booster, but also needs to slide onto the pin on the pedal arm.
If you study the situation a little bit, you will find that hole in the brake booster rod is very large, too large actually by design. As you press the brake pedal, the pin in the pedal arm takes up the slop in the booster rod. This "slop" is what activates the brake switch.
First off the switch is not mounted to anything solid. It floats back and forth with the brake pedal arm. So make sure the wiring has play, these wires move back and forth each time the pedal is depressed.
Second, it's a little confusing how the switch is installed. It pretty much takes two hands, and you are all twisted under the dash already. But the switch needs to surround the arm coming from the brake booster, but also needs to slide onto the pin on the pedal arm.
If you study the situation a little bit, you will find that hole in the brake booster rod is very large, too large actually by design. As you press the brake pedal, the pin in the pedal arm takes up the slop in the booster rod. This "slop" is what activates the brake switch.
Most of the time, it's just the switch that suffers damage. But, occasionally, the rod end gets worn and there is too much free-play in it, which will ruin a new switch in very short order.
I suspect this case may be the switch has broken on one end, allowing that plate to move more on one end, thereby causing the switch to move out of position. Wouldn't be the first......
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Fixed for now.
Thank you to all of you that helped out. I would have replied sooner, but I did not have the time to take on the switch replacement until today when the weather reached a nice temperature of 94 degrees.
I replaced the switch. Several bad words, back spasms, and WTF moments later it is working. The switch that I took out looked a little lopsided as far as the tension on the plate goes. Here's hoping the issue does not return. I will keep a lookout for the possibility that the issue could be the wearing down of the rod. It looked good and flat on the end and when I initially tried to mount the new switch I had it out of position leaning down and I could not force it up. I took that to be a good thing. When I put it in correctly, the switch had much less play in it than the one I took off.
Again, thank you to everyone. You guys are great.
I replaced the switch. Several bad words, back spasms, and WTF moments later it is working. The switch that I took out looked a little lopsided as far as the tension on the plate goes. Here's hoping the issue does not return. I will keep a lookout for the possibility that the issue could be the wearing down of the rod. It looked good and flat on the end and when I initially tried to mount the new switch I had it out of position leaning down and I could not force it up. I took that to be a good thing. When I put it in correctly, the switch had much less play in it than the one I took off.
Again, thank you to everyone. You guys are great.
Cargo Master
Joined: Jun 2008
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I just experienced this. I had replaced the booster and i put it on and off a couple of times, then like two months later I had to warranty the replacement booster. In the process I bent the fairly new (less than ten years old) brake light switch.
no amount of tweaking on my part trying to bend it back would get it to o function correctly once installed, and like posted above I could pull down slightly and it would illuminate.
I finally admitted defeat and was about to go get a new one then checked my spare parts depot in the garage and came up with one. And it worked perfectly after being installed.
I know how to put them on and off now without buggering them up but I used to fight them and damage would ensure to the very light switch frame.
My spare parts bag had the switch, on inside bushing (dark) and one outside bushing (white) just like what was on my 1980 bronco.
Of course I don't dispute Bill No.D. and never will also the diagram clearly shows two outside bushings but I see no way to get both on and have room for the pin.
no amount of tweaking on my part trying to bend it back would get it to o function correctly once installed, and like posted above I could pull down slightly and it would illuminate.
I finally admitted defeat and was about to go get a new one then checked my spare parts depot in the garage and came up with one. And it worked perfectly after being installed.
I know how to put them on and off now without buggering them up but I used to fight them and damage would ensure to the very light switch frame.
My spare parts bag had the switch, on inside bushing (dark) and one outside bushing (white) just like what was on my 1980 bronco.
Of course I don't dispute Bill No.D. and never will also the diagram clearly shows two outside bushings but I see no way to get both on and have room for the pin.
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My experience... 1980 F150 Ranger. Just struggled with the no brake lights issue. (Cause wasn't the switch but fuse) Simplest way to test the switch mounted, in my opinion, is put your multimeter's probes on either contact point of the switch. Set to lowest Ohm position. Not touching the brake pedal you should read open. Slightly press the pedal and watch the meter. You should see a different reading pretty quick which tells you the switch is functioning.
The right side bushing as shown in the illustration on my truck is there because of a larger piece that controlled part of (in the past) the cruise control cut-off. The right bushing is there and there is plenty room for the clevis pin still. (Personally, I'd call it more of a washer than a bushing, but that's just semantics)
With a bit of practice the switch comes off and on in less than a minute. Trust me... I had enough practice...
The right side bushing as shown in the illustration on my truck is there because of a larger piece that controlled part of (in the past) the cruise control cut-off. The right bushing is there and there is plenty room for the clevis pin still. (Personally, I'd call it more of a washer than a bushing, but that's just semantics)
With a bit of practice the switch comes off and on in less than a minute. Trust me... I had enough practice...
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