Trailer lights not working 2003 Silverado

Discussion in 'GM Electrical Tech' started by Highmarker, Jul 13, 2011.

  1. Highmarker

    Highmarker Rockstar

    I have a 2003 2500HD and I am not getting a right turn signal at the trailer light connection by the hitch in the rear. The fuse was burned out, so I have replaced it, but still no right turn signal. The right turn signal works on the truck. Where should I start? Do I start at the fuse and work my way back to the rear of the truck, or do I start at the trailer connection and work to the front of the truck?
  2. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    the fuse was gonna be my suggestion. check to see if it blew again. Are you hooking to the 4 or 7 pin. I had a similar issue and I know for the 4 pin they make a $4 tester light that plugs in and the stuff lights up (or blinks for the blinker). If everything shows fine on the tester then it means the signal is good all the way to the plug. which leaves it a trailer issue. If the fuses are good and the tester still shows it not working then it has to be in the harness somewhere. Since I didnt have the tester initially I just went to a trailer dealer and they hooked theirs up to see. I think napa sells a 7 pin tester.
    Last edited: Jul 13, 2011

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    x2.....On what David has mentioned......and I'll add the below Trailer Wiring Diagram,

  4. Highmarker

    Highmarker Rockstar

    It actually has the 6 - pin setup (1" diameter housing with 5 pins in a circle and one pin in the center). It was like that when I got it two months ago. I don't know why someone would change it out if it had the 7 pin setup.
  5. Highmarker

    Highmarker Rockstar

    So now I am finally getting back to fixing my trailer light problem. I have found the problem to right turn signal to be bad connection at the trailer connector, however I have no power to the center wire (RED). I have read here where that wire (along with the blue brake control wire) are not hooked up from the factory. See link below: diagram

    I don't know if this is true for a 2003 Silverado or not. I didn't see any wire underneath the master cylinder. My next step is to trace the RED wire all the way back to the battery and see if it is disconnected somewhere. Any suggestions would help out a lot. Thanks.
  6. Highmarker

    Highmarker Rockstar

    Come to find out that the 30 amp fuse was missing for the battery power to the trailer connector.
  7. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    glad that was all it needed

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