Question about 2003 Chevrolet Silverado 2500HD

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Trailer brakes I have a 04 Chev. 2500HD my trailer brakes worked when I first towed my enclosed trailer a week ago, now they wont work. rt & left blinkers, brake lights and clearance lights all work on the trailer... it is just the power to the trailer brake... the brake unit inside the truck has power to it and seems to be working fine, wiring seems in tact and no blown fuses. When the wiring harness is attached to the truck, the trailer brake doesnt recognize that anything is attached. Any ideas? clearly frustrated.

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Take a 12 volt test light... the kind that has a spring loaded clip to hold the probe into the wire, and insert it into the wire just before the trailer plug, vehicle side. (Blue I think) If there is a connection, the brake should see it and you should have an indicator light. When you activate the brake the test light should lite up. If not, move up to the brake actuator and test the blue wire. If there is nothing at the actuator, check the black wire. It is power to the controller. If no power there, check fuses again. If it does pick it up at the plug, connect the trailer and test the trailer itself. First ground to the trailer and then to the truck. Most problems are ground wire related. Then move to the axle and test it there. For the brakes to work, and even show on the indicator, there has to be a ground and power to the brakes themselves. There are 2 wires to each brake... a ground and a power. Test across both wires to make sure you have power and ground. You can also hook another trailer to your truck or another truck to your trailer. Lights can work through trailer ball ground. Brakes can't. leave the trailer unhooked from the trailer and hook the wiring up and test the lights. That usually will indicate a good or faulty ground. Also make sure there is a GOOD ground to the truck frame/body. Also try http://www.etrailer.com/faq-wiring.aspx. They have a great website with lots of info. Hope this helps. Mike

Posted on Oct 07, 2009

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  • Mike Tillman
    Mike Tillman Jan 29, 2010

    Check the ground to the brakes themselves. You can get a tester from http://www.etrailer.com/faq-wiring.aspx or take a "stab in" test light and connect it to the brake feed wire at the back of the truck and then on the trailer. The controller will pick up resistance or "draw" if there is a connection to that point. If you have power there, go to the axles and check connections.

  • Mike Tillman
    Mike Tillman Jan 29, 2010

    First check power on the truck. Use a "stab in" test light and connect it to the brake feed wire to the trailer. The controller will pick up "draw" and signal a connection. Then hook up the trailer and check it the same way in the trailer harness. Usually the blue wire. If you have power there, check connections at the axles. Also see http://www.etrailer.com/faq-wiring.aspx for more info. Ground is usually the fault.

  • Mike Tillman
    Mike Tillman Feb 11, 2010

    If you have one available, use a 7 pin tester that plugs into the truck plug. See if there is any reading there. You can also use a "stab in" tester and push the probe into the trailer brake feed wire.. usually large blue wire. With the tester hooked up with a ground, the truck should recognize a connection. If it does not, check all connections under the truck and re check the fuses. If there is power to that point, check the grounds on the trailer. At the brakes there are 2 wires to each brake. For the brakes to work there has to be power to one wire and ground to the other. That energizes the magnet that activates the brake. The ammount of voltage and resistance makes the magnet stronger or weaker. If there is no ground, you can run another ground wire from the frame, but MAKE SURE it is the ground side that you hook to.

    Hope this helps. Also try http://www.etrailer.com/faq-wiring.aspx.

  • Mike Tillman
    Mike Tillman Feb 11, 2010

    I have posted this answer 3 times and it gets rejected! Try http://www.etrailer.com/faq-wiring.aspx.

    Check grounds!

  • Mike Tillman
    Mike Tillman Feb 11, 2010

    I have posted answers to this post 4 times and it doesn't take the answer! Try http://www.etrailer.com/faq-wiring.aspx and check ground wiring to the brakes... under the trailer, at the brakes.

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Pull the plug apart on the trailer. Check that all wire connections are tight with a screwdriver. If it is a 7 pin plug the the terminal marked blue will have the brake wire in it. If it is a 6 pin plug it will be either the pin marked S around the side or the center pin, again check for loose wires. you must have a good ground because the lights still work. Also check the wiring under the trailer and around the axles for wires that may have caught something and been disconnected

Posted on Mar 09, 2010

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