Got an F250 Brake Light Question

Discussion in 'Mechanic and Repair' started by Allens LawnCare, Nov 22, 2007.

  1. Allens LawnCare

    Allens LawnCare LawnSite Senior Member
    Posts: 926

    Out of no where both my trailer and my truck brake lights stopped working, my blinkers work and they come on when I turn my lights on the just don't brighten up when the brake is pressed. I had two blow fuses both being trailer tow battery charge fuses.....Why I have no idea, I don't tow a trailer with an electric brake battery. I disconnected my trailer, changed both lights figuring maybe the wiring in my trailer is frayed and possibly shorted out....still no change. What are the chances its the switch on the brake peddle it self....it's an 03 250
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    It's a good chance the brake light switch did take a dump, Take your multimeter or test light under the dash and check for power into the switch and power out when the pedal is pushed.
     
  3. humble1

    humble1 LawnSite Silver Member
    from MA
    Posts: 2,499

    check the fuse box under the hood its black cover by the brake fluid. It could be one of those main fuses, i had similar problem mine was a 50 amp
     
  4. EagleLandscape

    EagleLandscape LawnSite Platinum Member
    Male, from Garland, Texas
    Posts: 4,347

    You're fusebox is underneath the steering wheel. Check all fuses, it could have shorted and blown a fuse. Also, a sensor could be out. Ie: brake pedal sensor underneath the steering wheel as well. If you have a oil change place that can read codes for you, go and try and do that.
     
  5. Allens LawnCare

    Allens LawnCare LawnSite Senior Member
    Posts: 926

    Here is the other thing I've noticed. When I press the Brake the Break light comes on over the cab.....any chance there are two points of contact in the brake switch
     
  6. humble1

    humble1 LawnSite Silver Member
    from MA
    Posts: 2,499

    yup fusebox under steering wheel and also main circuit fuses 20-50 amp along with relays are in the black box by the brake fluid, if you have a plow sometimes they cover it w/ the plow relay block but it is there. I have a f-250 p/u and a f-350 dump, my 50 amp fuse in this box went on the dump when a frayed power wire shorted that circuit i had the same symtoms.
     
  7. Allens LawnCare

    Allens LawnCare LawnSite Senior Member
    Posts: 926

    I looked for a fuse box under the hood and didn't see one, I do have two boxes but they look like relay switches.
     
  8. humble1

    humble1 LawnSite Silver Member
    from MA
    Posts: 2,499

    yup there are relays and the fuses are big. If you pop the top off the black boxes they are in there, what year is the truck? Its the same on my 1997, 1996, and pretty sure on my 05 thats where i mounted the plow block for the power and lights etc
     
  9. Allens LawnCare

    Allens LawnCare LawnSite Senior Member
    Posts: 926

    It's an 03 with an 8' fisher
     
  10. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    Obviously you did check the fuse, right?
    Right, so...

    Uhm you really need to get yourself a Haynes or a Chilton's Manual for that truck, but before you run to the store to get that...

    Do your hazard flashers work?
    Turn them on, see if all lights flash (walk around truck and trailer, every light should flash, front ones too).

    If they do then it's nothing to do with bulbs, or wiring.
    If they don't, well tell us :laugh:

    By now you should have a manual, and also always have an extra relay (or two).
    Buy 1-2 new ones if you don't have any, it comes in handy for troubleshooting to have extra relay.
    Replace the brake relay, if it has one, usually there's a diagram up on the INSIDE of the cover!
    If you don't have a spare relay, you could rotate the bunch and see if your problem relocates.
    > If it does, then your problem is a relay.
    > If it does not, the relays are fine.

    I'd tackle the brake light switch next:

    That's not a bad idea but for the trouble you go through to crawl up under there might as well replace it and be done with it.
    They're not super cheap but it's not that bad either, at least in my case I don't feel like crawling up in there but one time hehe

    I would replace that if all the above checks out, process of elimination.
     

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