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Pat
Pat 5/28/2012
2005 GMC Sierra 1500 HD SLE 8Cyl6.0L - Preventive Maintenance
Why no brake lights on truck but bulbs work for turn signals?
No brake lights on truck but the center cab brake light comes on, fuses and light bulbs are ok (not blown).
3 Answers
  • Jimm
    Jimm 5/28/2012
    May be related to a fulty brake light switch at the brake pedal. May also be related to a faulty brake light relay - though this same relay usually controls all the brake lights including the center high mounted stop light.
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  • Oxides
    Oxides 5/28/2012
    i ran across another gm where only the high mount stop light worked. in this case, the other brake lights ran through a different circuit, routing them through the combo switch. the combo switch was getting the signal from the brake pedal switch but not sending power to the left or right brake light. also, some bulbs have more than one filament. so check the bulbs and see if they look good. if no lights work then the stop light switch could be bad, or it could be a fuse. start working through the simple things first.
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    Oxides
    Pat 5/28/2012
    Thanks, I did check the fuses, going to go to store in morning and buy replacement bulbs just to make sure. One thing I forgot when I posted is my bed is a Chevy bed. I was T-Boned a couple of years ago and they couldn't get a new GMC bed so they ordered a new Chevy bed and the lights are different from my manual. I was told it may be the brake pedal relay so may pick one up also. Thanks again.
  • HouseCallAuto
    HouseCallAuto 6/1/2012
    the turn signal switch (combo switch like Oxides said) is junk. probability here is greater than 90%. Hi mount stop light bypasses the TSS, separate circuit from the rear brake lights. This is not that uncommon as I have dealt with this before once or twice over the years, always on a GM truck.
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    HouseCallAuto
    CVO 6/1/2012
    Maitre HCA. Ca fait longtemps que je n'avais pas recu de vos nouvels. Soyez la bienvenue et merci pour le bon retour.
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