1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

Got the master cylinder on my F100 replaced and now the brake lights stay on, why?

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Old 02-26-2013, 09:20 PM
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Got the master cylinder on my F100 replaced and now the brake lights stay on, why?

Any ideas why? Today after I picked up the truck from the mechanic. I realized that when I parked my brake lights were on. Even after i shut off the engine.
I then pressed the brake pedal ant they came off. No power brakes.
Any ideas what is happening?
Thanks in advance
 
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Old 02-26-2013, 09:35 PM
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Does your truck have power brakes?
 
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Old 02-26-2013, 09:44 PM
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No power brakes.
 
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Old 02-26-2013, 10:05 PM
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'had that issue with my 68 Mustang... had a sticky brake light switch.
 
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Old 02-26-2013, 10:06 PM
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How do you fix that?

Originally Posted by HIO Silver
'had that issue with my 68 Mustang... had a sticky brake light switch.
 
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Old 02-26-2013, 10:08 PM
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Sounds like brake switch is shorted or improperly adjusted . Ck brake lamp switch .
 
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Old 02-26-2013, 10:20 PM
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break light

you may have air in the area of the switch. try bleeding the master or loosen the switch on the line and bleed it like you do the calipers.
 
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Old 02-26-2013, 10:33 PM
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Originally Posted by peckman
you may have air in the area of the switch. try bleeding the master or loosen the switch on the line and bleed it like you do the calipers.
Does his truck have a hydrolic brake switch ? It may be stuck or shorted . I thought they were on the pedle assy like my 78 . Ck brake switch anyway , sounds like your problem .
 
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Old 02-26-2013, 10:40 PM
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Originally Posted by Vsanzbajo
How do you fix that?
 
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Old 02-26-2013, 10:58 PM
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look below the master cylender near the stearing shaft there should be a block the lines screw into it was not normal for these trucks to have them....if there is one on the pedal assembly then pull up on the pedal and see if the lights go out...if it does you can just adjust the switch closer to the pedel arm.
 
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Old 02-27-2013, 07:25 AM
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Got the master cylinder on my F100 replaced and now the brake lights stay on. Why?

Originally Posted by Vsanzbajo
Today after I picked up the truck from the mechanic, I realized that when I parked my brake lights were on. Even after I shut off the engine.

I then pressed the brake pedal and they came off. No power brakes.
The brake light switch is now out of adjustment after the master cylinder was replaced. Typical.

The switch (D2TZ-13480-B / Motorcraft SW-691-A) is threaded and adjustable.

It's located on the brake pedal itself, threads into a retainer (C8TZ-13A629-A) that attaches to the pedal.

1964/72 Ford Truck Parts Catalog / Illustration Section 75, Page 21 ~ 1969/72 F100/350 Brake & Clutch Pedals & Related Parts.

Fordification.com has this catalog on their website, take a look-see at this parts catalog pic.

(sigh) Pay no attention to info in posts 7 & 10. Has nothing to do with it and it's malarky!
 
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Old 02-27-2013, 07:37 AM
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Originally Posted by NumberDummy
The brake light switch attaches to the brake pedal and is adjustable as it has threads.
Yep ND is correct on this one. Unhook the wires to the switch, rotate the switch clockwise to get the switch closer to the stop so there is 1/16" clearance. Simple.
 
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Old 02-27-2013, 07:52 AM
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Look on the brake pedal, about 1/2 way up. Like mentioned, likely the pedal is hanging closer to the floor and the switch needs adjusted down to touch.

You should be able to hear the switch click when you push it. Turn it down til you hear it click with the pedal up.
 
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Old 09-25-2014, 10:38 PM
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I have kind of the same issue but I think the brakes are sticking or something when I press the brakes the peddle dose not appear to return and I don't think the rear drum brake release all the way. but if I pull the peddle up with my foot feels like the brakes release. any Ideal what I should be looking at? The return spring in the rear drums the power booster?
 
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Old 09-26-2014, 10:12 AM
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Check to see if ND's instructions solve your problem.

If it turns out to be properly adjusted already, go with HIO's suggestion.

"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
 

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