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'04 2500 HD trailer plug problems

Discussion in 'Chevy Trucks' started by Motorman 007, May 25, 2006.

  1. My '04 has the trailer tow package with 7 pin connector. The right directional and brake light don't work when I hook up either trailer that I use. There is no power to the connector on the truck. I even pulled apart the back side of the truck plug, no power. The directional on the truck works. A friend told me that each turn circuit was fused, but I cant find it in the fuse box under the hood. Any ideas guys???
  2. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,990

    Yes the tow pack is fused separately from the truck. I believe it is in the power distribution box under the hood if you cann't find it there try the fuse block on the drivers end of the dash or look in your owner's manual.
  3. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    MOTOR...............GM switched some of the pin arrangement
    around 03 as did trailer mfrs...............
    I had this issue when I went from my 01 to my 04. You
    really need a test light to determine the pin out arrangment !

    You will also have to insert a 30/40 amp maxi fuse in either stud 1
    or stud 2 (forgot which) in the underhood fuse center to power
    up the hot lead for trailer aux. power line. Not always necessary
    to do so tho.

    Check this link for current GM truck pin out and read attached
    cautions also posted there......................
    http://marksrv.com/wiring.htm ................geo:drinkup:
  4. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,990

    This only pertains to the Brake control jumper harness they swapped pin locations for the illumination feed and the brake signal feed on the under dash b/c adapter not relevant to your problem
  5. Thanks Guys,
    I've done the test light routine. There is no power in the green (rt) directional wire on either side of the trailer plug. I've been in the box under the hood and there are several trailer related circuits, just not one for the left and right directionals. I'll keep looking.....
  6. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    BAsher.........READ the cautions on that Marks RV link posted above.
    It CLEARLY cautions and mentions to check ALL pinouts on ANY GM
    truck.............Seems somebody was asleep when they wired these
    bad boys up !!!!!!!!!!

    There are MANY reports on several GM truck sites with the trailer
    plug wiring being messed up or wired differently than the printed
    literature. So caution and common sense must be used

    There was also issues with some aux. power wiring NOT being
    connected UNDER the underhood fuse center...............

    Changing the pin outs on my trailer brake controller was a piece of
    cake to make it work from my 01 to my 04 with info. found on the

    The rear connector pin out was the problem I had and Motor is having
    now. But some common sense and help from fellow GM owners
    and a few pin out changes fixed me up..........geo:drinkup:
  7. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    MOTOR.......I have my owners manual handy and heres the scoop:

    "The eight wire harness contains the following trailer circuits"
    yellow..left stop and turn
    dark green... right stop and turn
    light green...back up lights
    light blue....center mount stop light
    red....battery feed.........requires installing maxi fuse underhood
    but will NOT effect trailer light operation !!!!!
    Dark blue.....trailer brakes
  8. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,990

    Sonjaab; Of course the general's build quality is pi$$ poor. But until Motor identifies that the fuse is good, and there is a fuse, I wouldn't start looking for incorrectly wired connectors. If all the other functions are correct then the first step is find and verify the fuse. Then I would start looking for a example of GM manufacturing ineptitude. I see many GM trucks, the number of incorrect or incomplete wiring pales in comparison to the number of blown fuses. Always verify the power chain, once you find the source of the Nile (so to speak) if the fuse is intact you can attach a toner and track the open or shorted circuit. But first check the simple stuff.
  9. 4speed

    4speed Member
    Messages: 93

    motorman, when you open your drivers door ther is an access panel to the fuses on the side of the dash. on the right side about half way up there are 4 red fuses together (10amp)the ones to the left are for trailer stop & turn. upper is for left side , lower is right side. hope this helps.
  10. Thanks 4 speed!!

    That's what I needed! The RT Trailer fuse was blown. Thanks so much!