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Discussion Starter #1
When I hit my brakes lightly my brake lights don't turn on but when I hit them hard they turn on is there are switch on the pedal that needs to be replace or adjusted or could it be the lights themselves?
 

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is there are switch on the pedal that needs to be replace or adjusted
Yes. I don't think that there is an adjustment and that it just needs to be replaced, but you can check it before you buy a replacement.
 

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yo,
As Joe 'splained;
also.. Switch Adjustment using a F 350 Switch in a 90
Source: by buggzz at FSB

an Excerpt;
"...I went to my friendly pull-n-save junkyard and grabbed a brakelight switch from an F150 and from an f350. The f350 switch is sprung much lighter, just like you guys said.

first I put on the f150 switch, which is identical to the bronco switch (no big surprise there). but the brake lights still acted like before, I have to press the pedal a little harder than "stopped at a light" to get the brake lights to light.

Then I put the f350 switch on with the bushing. Same results as before, I have to press harder than "stopped at a light" to get brake lights. tried the f350 switch without the bushing, and voila! If I press the brake pedal about 1/4" I get brakelights. the lights stay on until I take my foot off the pedal, and I don't get any "false" brakelights over bumps or traintracks..."
 

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There are usually 2 kinds, one that is a plastic cylindrical plunger looking thing that mounts to the pedal and the other is rectangular metal with a hole that mounts to the pushrod. The pedal mount one does need to be adjusted so that it releases the plunger with minimal pedal travel.
Alternatively, you could skip both of those and put a switch inline with the brake lines that senses the fluid pressure. A little more work but I would think it will be more reliable and accurate.
 

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The BOO is the rectangular switch wrapped around the MC pushrod at the pedal, and there is no adjustment. Bottom center of this diagram:



If you brake light behavior has changed, it indicates a problem in the booster:

 

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Discussion Starter #6
So I installed a new switch and of course didn't think to check it well I got pulled over tonight luckily I was the dd so the cop let me off he was looking for the bog ticket dui. Anyways what else could be causing the brake lights the come on only after hard braking. Now I'm hand signal for brakes
 

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I found that you can install the switch upside down and cause what you are describing (don't ask how I know :doh0715:)
Use the diagram provided by Steve83 to make sure yours is installed properly.
 

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The BOO is the rectangular switch wrapped around the MC pushrod at the pedal....
BOO switch... wow, haven't heard that lately... took me a minute. Some of the techs at work would call it a BOO switch or just a brake light switch. First time I heard it, I was like, 'scuse me? Haha...
 

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Well I went to a JY and picked up a BOO from a F-350. Installed it and it was far worse than before! Brake pedal was almost to the floor before the lights came on.

Well I was wondering where I went wrong and started to think that maybe it was a 250 not a 350, and I grabbed the wrong part or something.

Then I read this:

I found that you can install the switch upside down and cause what you are describing (don't ask how I know :doh0715:)
Use the diagram provided by Steve83 to make sure yours is installed properly.
Works great now. :doh0715:

Here are picks of the two different BOO switches:
Original on right. f350 on left


Other side, F350 on bottom


I know its an old thread, but its useful, and I added pictures!
 
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