Trailer Brakes Do Not Work on a 2003 GMC 2500 With a Factory Tow Package

Question

Question:

I have a 2003 GMC 2500 with a dura Max engine. Factory tow package .my problem isthat my trailer brakes do not work. The problem seems to be with rt he pick up. Any ideas

asked by: Howard B

0

Expert Reply:

To start off you need to check under the hood to make sure the wiring connection mentioned in the GM brake controller FAQ article attached are made. In the 2002 - 2003 model years, GMC changed the way you hook up the brake controller under the dash. There are two possible wiring adapters that will fit the connector under the dash. The 3015-P and the 3025-P. The only difference between the two is the way the RED wire is pinned out. The red wire carries the signal from the stop light switch, telling the controller when the trucks brake pedal is being pressed. If you have the wrong connector, the controller WILL operate with the manual control, but NOT with the brake pedal.

I have attached a short installation video for a 2005 GMC with the # 3015-P.

If all this checks out okay, then check out the FAQ article I have attached on troubleshooting brake controllers.

You might also have a blown fuse. In your fuse panel, inside the compartment should be a legend listing the fuse locations. Check the fuse for the brake circuit and replace it if you determine it was blown.

The next step would be to check the brake pin on your tow vehicle. Use a circuit tester such as Quickee # 3808 and check the pin located at 5:00 for voltage. If no voltage registers, then check the pin for corrosion or damage. A bent pin can negate the voltage thru-put. I have attached a FAQ covering trailer wiring.

If you find that your problem does lie in your factory connector, the Pollak Trailer Connector, # PK11916 that you referenced is the correct replacement part.

expert reply by: Lori W

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Answer 1

I am assuming you are speaking of the fuse that activates the power feed to the brake controller. The 30 amp fuse is installed in the power distribution box as shown in the photo I have edited. The power distribution box is located under the hood,…

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Answer 2

There are actually a few connections you will need to make under the hood to get the brake controller and tow package fully functional on your 2003 GMC Sierra. Under the hood, on the drivers side towards windshield, there is a bracket you will need…

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Answer 3

The 7-Way trailer connector on the back of your 2003 Chevy Silverado should have a round plug behind it that plugs into another harness that continues up to the front of the truck. What you can do is use #C55774 which comes with a new mounting…

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Answer 4

See the picture to the right for a wiring diagram of seven-way vehicle end trailer connector. If you click on it you can enlarge it. I have also included a trailer wiring FAQ page for you to check out.

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Answer 5

It's actually easier to activate the brake controller wiring of your 2003 Chevy Silverado so that you can use the part #3015-P that you referenced. There are just a couple connections you need to make under your hook and you'd be set. If you…

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Answer 6

First, make sure that your #3015-P harness is pinned out correctly. The red wire should be in the bottom left location (if looking at the back of the end that plugs into the truck). Directly next to the red wire should be the blue wire. Above the…

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Answer 7

There are a couple of items that are causing your brake controller problem. The problem can be caused by either the stoplight wire incorrectly installed, or the adapter you are using is not designed for the brake controller you have. The plug-in…

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Answer 8

What you are describing is normally the result one 1 of 3 issues: First, there could be some corrosion in or on the connectors on the vehicle or trailer side or both. Second there could be a bad ground. Bad grounds can cause all sorts of bizarre…

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Answer 9

To determine why you do not have any power on the blue brake output wire, I recommend starting at your brake controller. First, make sure the brake controller is on and receiving power. Most brake controllers have 4 wires, blue (brake output to…

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Answer 10

Discovering why the trailer brakes are not getting power will be a process of elimination. I am not aware of what you have and have not checked, so I will describe the whole troubleshoot process. Start with the brake controller itself. Is it properly…

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Answer 11

Sounds like you are referencing the blue wire of the 7-way round connector like what's in the attached picture. If you have no use for an additional 12 volt circuit then it would not be needed. It isn't always needed so it sounds like you may…

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Answer 12

The blue wire on a trailer is typically the output wire to the electric brake assemblies. If this is the case on your trailer then the wire should only have power when you are hooked up to the tow vehicle and are applying the brakes, either by…

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