Brake lights stuck on

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by KEB1, Jul 5, 2022.

  1. KEB1

    KEB1 Bobtail Member

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    Jul 5, 2022
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    I have a 2012 international pro star and my brake lights are stuck on …I changed out brake light switch u see the dash by the steering column still stuck on …. I unplug them each night so won’t drain battery down and unplug trailer as well …. When I start the next day I plug tractor lights back on and trailer as well no brake lights come on for trailer but tractor it does and once air pressure builds up brake lights for trailer stay on as well !!! Anyone have had this problem and what did you do to fix it I traced wires back to brake light on back of the rig nothing shorted or worn !!! When I got home today I pushed pedal till all the air was out and brake lights on trailer went off but tractor stayed on would the foot pedal on firewall need to be replaced
     
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  3. Inderjit

    Inderjit Medium Load Member

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    Is the hand valve slightly pulled back?
     
  4. baha

    baha Road Train Member

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    Are you sure that the brakes are free of air going to them, with the wheels chocked push in both emergency buttons and take the blue line off the trailer to see if air is coming out, if not ck truck brake arms to see if they are tight against the drums! If not then start looking for rubbed wires in the brake light harness? If you have air going to the brakes the foot valve is bad but be sure that the pedal is coming all the way up to release the air to brakes?
     
    Last edited: Jul 6, 2022
    Bean Jr. Thanks this.
  5. FLHT

    FLHT Medium Load Member

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    Floor mat under foot pedal ?
     
  6. 062

    062 Road Train Member

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    Do you have a full 12v at the plug or is it something like 7v? If it’s low voltage I would look for pinched wires or corrosion inside a plug creating a bridge.
    @Heavyd
     
  7. Judge

    Judge Road Train Member

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    there used to be a plunger on brake pedal that was bad about letting pedal stay down a bit to activate brake lights
     
  8. Inderjit

    Inderjit Medium Load Member

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    You need to scan it with Diamond logic Builder to see the state of the brake light switches.
    There is a possibility that the software in the electronic system controller is corrupted and needs to be reflashed.
     
    Heavyd and spsauerland Thank this.
  9. Heavyd

    Heavyd Road Train Member

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    Like mentioned, check the pedal and trailer spike handle are in the fully released position. If you drain completely all your air and the lights do go out, then you have a brake valve sticking or leaking internally and that will need to be tracked down. If the lights stay on with no air pressure left in the system, then this is an electrical/electronic problem that will need Diamond Logic software connected to see what the body controller is doing.
     
    spsauerland, 062 and AModelCat Thank this.
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