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Adding a 7-Way to Bumper and Bed of a 2012 Ram 2500 that Originally Came with a 7-Way


i have a 2012 ram 2500. when i bought it the factory 7 pin trailer plug located in the rear bumper was missing and one was installed in the bed for a gooseneck. the wires to the plug are different colors and spliced in to the factory wiring. long story short it was done incorrectly. i want to leave the bed plug and added a plug back in the bumper but i cant seem to figure what color wires are what, even after disconnecting them and testing each one with a multi-meter, i cant figure it out. if anyone can help me that would be great. the factory wires at the harness tail are as follows: green brown black white/orange stripe white/blue stripe black/gray stripe red/purple stripe white/green stripe


Expert Reply:

Usually when there is a question on the function of a wire the solution is to test that wire. But you indicated that you have tested the wires and still cannot figure out the functions. But you didn't say why that is. Were you getting conflicting readings from the meter? A meter might be a little too sensitive for this test. Really all that is needed is a circuit tester such as # PTW2993.

Two of the wires will show power when the brake pedal is pressed. And one of those wires will also have power with the left turn signal while the other will have power with the right turn signal. Another wire will have constant power. This is the 12-volt circuit. One wire will have power when the truck running lights are on so it is the running light wire.

One wire may have power when the truck is in reverse. One will only have power if a brake controller is activated. And the last wire is the ground. That should help to narrow things down some.

Take a look at the picture I have included that shows the functions of a vehicle side 7-Way connector. Ignore the colors and just focus on the positions of the functions. that will help out quite a bit since I can't tell you what the functions of the wires you have are.

Another way to go about this is to completely remove that in-bed harness and the wires spliced in. There should be a harness with a rectangle connector under the truck that the original factory 7-Way at the rear plugged into. To replace the connector at the rear of the truck you would just need # HM40975-11933.

Then to add a 7-Way back to the truck bed you can use # 41157 which will plug in line with # HM40975-11933.

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