2000 peterbilt 379 headlights stuck on high beam

Discussion in 'Peterbilt Forum' started by grampak, Aug 9, 2022.

  1. grampak

    grampak Bobtail Member

    1
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    Aug 9, 2022
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    Just bought this 379 pete awhile back and i cant get the headlights to dim. I have disconnected the blinker dim switch and that does nothing. I have swapped relays around on the fuse panel. I have one schematic that shows a MFTS module, but if there is one I cant find it. Looking for any kind of help.
     
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  3. lester

    lester Road Train Member

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    Jan 2, 2012
    NW, Iowa
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    You sure you don't have a blown fuse or tripped breaker? I forget which one it is but there's on that will make that happen. It's not the headlight breaker
     
  4. 062

    062 Road Train Member

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    Are they just barely burning or full bright?
    If just barely, then you have a bad ground on the low side.
     
    Coolbreezin Thanks this.
  5. Coolbreezin

    Coolbreezin Light Load Member

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    Jun 11, 2016
    Florida
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    I have a '91 379 and I recently experienced my high beams wouldnt come on and neither did the dash high beam light. It was a breaker on my fuse box on the floor by my clutch pedal. Pressed it in and all is fine now.
     
  6. SmallPackage

    SmallPackage Road Train Member

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    Marion Texas
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    Open up the headlight pods on grill by removing the bulbs to check wires just to make sure that the high and low beam wires aren't melting together causing the highs to be on. It happens. Rare but happens.
     
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