Troubleshooting Trailer Connector on 2004 Chevy Silverado

Question

Question:

I have a 2004 3500 dually Chevrolet long box have always had lights to my trailer plugged in and nothing I am thinking for all the lights to not work it is my ground where do they ground the trailer connector to my truck do they run a wire to my batteries diesel

asked by: Tom W

1

Helpful Expert Reply:

The first thing you'll want to do is determine if the problem lies with the trailer or the truck.

Can you try the trailer with another truck or the truck with another trailer? That'll tell you pretty quickly where the problem lies. Another option would be to use a circuit tester like part # PTW2993. Have a helper activate all the taillight functions one by one, as you test the pins on the trailer connector. I'll link you to an FAQ article that shows what signal you should be getting on which pin.

If you're not getting any signal at all, or if they're erratic, it could very well be a poor ground. The trailer connector on the vehicle is usually grounded to the vehicle frame somewhere at the back of the vehicle. You can trace the wiring harness from the trailer connector to find the grounding point, and make sure its tight and not corroded. Also test the ground on the trailer, which is usually found on the trailer tongue.

Check the trailer connector on the truck and the trailer. If it's corroded or damaged, you'll want to replace it. The # HM40975 would be an excellent choice.

If the grounds are good, there might be blown tow package fuses. The fuses are located in the fuse box under the hood on the driver's side inner fender. The lid of the fuse box will have a diagram showing which fuse protects which circuits.

I'll also link you to our trailer connector troubleshooting FAQ article.

expert reply by: Mike L

1

Answer 1

That is a pretty odd issue. Since the fuses look good, and you do not see any obvious issues with the wiring I would check that there is no corrosion causing power to jump from the 12v power pin to the other pins, as this would be the most likely…

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Answer 2

For a replacement 7-way confirmed to fit your 2004 Chevy Silverado 2500HD we have the part #74682 which is a fit that also has a 4-way on the side of the 7-way. I attached an install video for this connector for you to check out as well.

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Answer 3

When hardwiring a 7-Way to your 2005 Chevrolet Silverado, like part #PK12-707E, you will want to connect the following functions to the following pin locations: 1 o'clock - 12V Power 3 o'clock - Right Turn/Stop 5 o'clock - Brake…

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Answer 4

You have some wiring shorts that need to be cleaned up. It sounds like your best option is to go over all of the trailer wiring on the truck. I'd suspect that if you inspected the back of the trailer wiring connector you'd see quite a bit of…

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Answer 5

Most likely the issue you're having with your trailer lights not functioning is due to a weak ground. The tester you use on the truck's socket does not draw much power at all, nowhere near the current drawn by the actual trailer lights when…

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Answer 6

It sounds like you may have a loose wiring connection or a corrosion problem on the 7-way pin for the right turn/brake lights. This pin is the one at the 3-o-clock position as you're looking at the vehicle's 7-way; please refer to the linked…

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Answer 7

It sounds like you're asking about the 12V circuit on the 7-way trailer connector on the rear of your 2003 Chevrolet Trailblazer. Some vehicles will always have power and some others will not. We don't have this specific information for your…

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Answer 8

Most GM trucks use a pretty standard wire color for their tow packages, but I always recommend testing for function, and not just color. If you follow the bundle back there should be more wires than the ones you mentioned, for a total of 8.…

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Answer 9

If your Silverado has the factory plug located above the spare tire, the easiest way to install a 4-pole would be to use the Tow Ready #118384. Simply remove the protective cap covering the plug, plug in one of the connectors on the Tow Ready Harness…

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Answer 10

For a 6 way round connection, like you find on the Hopkins Adapter 4 Pole to 6 Pole and 4 Pole Trailer Wiring Adapter #37175, the ground wire will be located in the 2 o'clock position as you face the connector. The back of the connector (10…

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Answer 11

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 12

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Troubleshooting Trailer Connector on 2004 Chevy Silverado

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