Re-Wiring a 2002 Chevrolet Silverado that had a 7-Way Cut Off

Updated 05/10/2010 | Published 05/07/2010

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Question:

I have a 2002 chevy silverado that I believe had a 6way trailer plug on it. the plug has been cut off and there are just 6 wires coming from the spare tire, that run into the stock wiring. I tow a car trailer with electric brake and a small trailer with just 4way plug. I would like to hook them both up and if possible wire in a 12v source for my whinch on the car trailer if i can do that with this part #HM40975. The car trailer as of now has a 4way plug on it for the lights and I dont have the electric brake ran to the truck yet. I spent all day trying to wire up the 4way plug but Im not able to get the harness to work. would the 7way / 4 way plug work for my needs or is there something else I need to do inorder to run all the lights and electric brake for the car trailer. would the factory harness have the electric brake wiring or do I need to run a wire from the brakes.

asked by: Rob S

Expert Reply:

Part # HM40975 is a plug-in unit if your truck is pre-wired and has the right connector. There is another part that you can use that will accomplish the same, but has wire leads instead of a fitted connector back so you can connect them to the loose leads on the truck.

Use 7-Way like, part # 37185. You will need to cut off the 4-Way connector so you can have the yellow, green and brown wires loose. Use a circuit tester, like part # PTW2993, to identify the 6-Wires by their function.

Turn the truck on. With head lights OFF, you should have one of the wires active. Label this one as your 12V power, it will be connected to the black wire on the 7-Way. Turn on the truck head lights. The circuit that is now active is your running lights, and should be connected to the brown wire on the 7-Way. Turn on the left blinker, identify this wire and connect it to the yellow wire on the 7-Way. Turn on the right blinker and connect this wire to the green wire. The white wire gets grounded to a clean metal area of the truck frame.

At this point you will have 2 wires left on the truck and 2 on the connector. One should be for reverse lights, the other for the brake controller. Have someone put the truck in reverse while applying the foot brake. The emergency brake should also be activated. Identify which wire is hot, and that would be the reverse wire and should be connected to the purple lead on the 7-Way. The last lead should be for the brake controller and should be connected to the blue lead on the 7-Way.

If you find something contrary to what I have outlined, please write back and let me know what you have found before you connect any wires. It would be best to identify all those wires first, and then connect them to the 7-Way.

Once you have wired the 7-Way, you should be able to plug a brake controller into the port underneath the dash. Your 2002 Silverado would have come with a pre-wired brake controller port that we should have re-activated by wiring in the 7-Way above. I would recommend the Tekonsha Prodigy P2, part # 90885 and vehicle specific wiring harness # 3025-P.

expert reply by: Patrick B