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Thread: Left Trailer Brake Light Not Working

  1. #1
    Join Date
    Jul 2003
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    Woodbine, MD
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    Left Trailer Brake Light Not Working

    Truck is a 2003 Silverado 4x4 1500 ExtCab

    I have no power, 12v at the factory installed 7 pin trailer connector for the Left Trailer Brake Light. This is the yellow wire. Fuse is good, location of fuse am talking about is inside the cab, by drivers door, on the end of the dash. One side of the fuse holder is hot.


    Where is another good location to check for 12v and where a break in the wire might be located?
    Orest


  2. #2
    Join Date
    Jul 2002
    Location
    NC
    Posts
    1,690
    Check the ground wire on the trailer. Check the ground at the truck. Just went thru this and mine was the right side.

  3. #3
    Join Date
    Jul 2003
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    Woodbine, MD
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    This is wiring problem on my truck

    not the trailer. Every other light on the trailer works.

    Since the yellow wire on my truck is dead the trailer brake light won't work.

    I guess I'll have to open the wire bundle somewhere in the middle of the chassie and see if I can find the yellow wire. And check it there.
    Orest


  4. #4
    Join Date
    May 2006
    Posts
    6
    Check your fuses. I had a similar problem and it turned out to be one of the under the hood.

  5. #5
    Join Date
    Oct 2007
    Location
    Waxhaw, North Carolina, United States
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    1,167

    I Can Help

    If the brake and turn signals on your truck are working with the trailer disconnected, it will not be a fuse problem. If they are not, but the fuse appears good and you get power on top of the fuse, run the point of a test lamp down beside the fuse and touch it to the contacts the fuse slides into. I have seen (more than once) a fuse receiving power from the battery side, energizing the fuse on both side and have corroded contact on the lamp side resulting in no power to the lamps. Also brake and turn signals run through your turn indicator switch and it could be faulty.

    If everything there checks out, go back to the 7 pin connector, with the turn signal on and check for power, if nothing scratch the contact with the test lamp, if still nothing, with the test lamp probing the terminal, take the harness and wiggle and twist it around. If this lights your test lamp, you more than likely have a broken wire. Note, the wire casing does not have to be broken, the wire strands could be fractured inside the casing, and to find this all you have to do is pull on the wire and the casing will stretch and break.

    Do these checks and post with your results. I'll be glad to help resolve this problem


    PS make sure your test lamp is working by touching a known good power source at the point of service.

  6. #6
    Join Date
    Jul 2003
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    Woodbine, MD
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    Racewire20

    Thanks for the reply. I will try and test the the fuse socket this weekend, with the fuse in place. I wiggled the 7-pin connector and the yellow wire itself and there is no power there, I need to find a good point between the fuse and 7-pin connector to pin point the break.

    Every other light on the truck and the trailer work except the trailer left brake light, whic h is powered by the yellow wire.

    It's only a 4x8 utility trailer and you can see my truck brake/turn signal from the rear; but it's the point that it doesn't work that is bugging me.
    Orest


  7. #7
    Join Date
    Oct 2007
    Location
    Waxhaw, North Carolina, United States
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    Orest, follow the trailer harness on your truck to the point it connects to the trucks rear harness, I'm not sure for your truck, but most later models will have a connector to allow adding on the tow option. If so disconnect this connector and check the circuit at that point. If the trailer harness looks like it is an aftermarket add on, check for proper connection,at splices, if improperly sealed from moisture you could have a corrosion problem.
    If you still have no power at that point go up to the cab, find the rear harness (probably in the LH kick panel ) find the yellow wire and pierce it with your test lamp and see if you have power there,if not work your way towards the fuse panel piercing the wire every 6-10 inches till you get to the problem, if you do have power at that point the work your way to the rear,piercing the wire the same until you find your problem.
    Also just look over the harness first for any damage (cuts,pinches,breaks,etc).

    PS; Failed to mention, do all these checks with the key on, LH turn signal on or someone holding the brake pedal down.

    Good luck, and post an update.

  8. #8
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    Racewire20

    I haven't had time to search this any further; but, I will post an update when I do.
    Orest


  9. #9
    Join Date
    Feb 2005
    Posts
    360
    [QUOTE=Orest;448252]Truck is a 2003 Silverado 4x4 1500 ExtCab

    One side of the fuse holder is hot.
    QUOTE]



    shouldn't both sides of fuse be hot, if fuse is good?

  10. #10
    Join Date
    Mar 2008
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    Midlothian VA
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    946
    just make right hand turns!

  11. #11
    Join Date
    Oct 2007
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    Waxhaw, North Carolina, United States
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    [QUOTE=dawgfsh;459519]
    Quote Originally Posted by Orest View Post
    Truck is a 2003 Silverado 4x4 1500 ExtCab

    One side of the fuse holder is hot.
    QUOTE]



    shouldn't both sides of fuse be hot, if fuse is good?
    Yes, If the fuse is good, you will be getting power on both sides. However I have seen cases where the fuse was not making a good connection at the box.
    So when checking fuses I always slide my test lamp beside the fuse to the contacts in the fuse panel to check to make sure that power is passing through the fuse to the other side of the circuit in the box.

  12. #12
    Join Date
    Feb 2009
    Location
    Maryland
    Posts
    1

    Left trailer brake light not working

    Does this Chevy have amber turn signals? If so, check the wiring at the converter (yellow wire)and see if it has 12volts coming out of it. I have seen these go bad and have brake/signal voltage on the incoming side of the converter ..but not the other side going to the 7 way. Keep us posted!

    Tmac

  13. #13
    Join Date
    Oct 2007
    Location
    Waxhaw, North Carolina, United States
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    Quote Originally Posted by Tmac View Post
    Does this Chevy have amber turn signals? If so, check the wiring at the converter (yellow wire)and see if it has 12volts coming out of it. I have seen these go bad and have brake/signal voltage on the incoming side of the converter ..but not the other side going to the 7 way. Keep us posted!

    Tmac
    I don't believe this truck has euro style lighting incorporating an independent amber directional signal.

    Plus this post is so old I think Orest has had to buy a new truck
    The 03 is rusted out by now.

  14. #14
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    Oct 2007
    Location
    Waxhaw, North Carolina, United States
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    Tmac, I owe you an apology, You are correct in the fact that that year model chevy truck does have amber rear signal lamps. My bad

  15. #15
    Join Date
    Jul 2003
    Location
    Woodbine, MD
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    Still got my truck

    just haven't had the time to mess with this problem.

    Trying to get a house ready to put on the market.

    When I discovered the problem I was using my little utility trailer to haul some stuff around.


    And there is not a spot a rust on it ....


    Thanks for all the replies.
    Orest


  16. #16
    Join Date
    Feb 2009
    Location
    Baltimore, Maryland
    Posts
    215
    I had the same problem, now have the engine removed, working on the transmission, thought it might be a short from the glow plug, but its not a deisel. Hood is now off, all brakes removed, pulled all wire harnesses, and would'nt you know it , a spider got into the connection plug. Anyone know how to put this all back together? I numbered the parts but done with a piece of chalk and it rained. I am in ALOS>

  17. #17
    Join Date
    Jan 2001
    Location
    clinton, md
    Posts
    676
    Quick and dirty fix. My Tahoe had the same problem. Uhaul sells replace bulbs with wire leads for those people without factory installed trailer harnesses. Replace your bulb with the Uhaul bulb and splice the lead with the yellow wire. Problem solved 30 minutes total.

  18. #18
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    Jul 2003
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    Woodbine, MD
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    Thanks for the great idea.
    Orest


  19. #19
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    Jan 2001
    Location
    clinton, md
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    676
    Even a broken clock is right twice a day.

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