How to Determine the Wire Functions for 7-Way Trailer Connector on a 2002 Dodge Ram 1500  

Question:

Helpful Expert Reply:

The only way to know for sure what the functions of the factory wires are on your 2002 Dodge Ram 1500 is to test them with a circuit tester such as # PTW2993 or a meter if you have one.

Testing the light functions is easy. have someone sit in the truck to operate the lights while you test the wires at the back of the truck. I recommend writing down or labeling the wires for future reference. That will take care of the running lights, turn signals/brake lights, and potentially the reverse lights. But be sure that the emergency brake is on, wheels are chocked, and the person in the truck is holding the brake pedal down while you are testing for reverse lights. Safety first!

There will also be a 12-volt power wire which will have constant power. The truck may have to be on for it to have power though.

The 2 most difficult wires to test are the ground and the brake output wire. If you have a brake controller, then it makes it easy. You would just have someone apply the manual override on the brake controller (on and off, on and off) to find the right wire. That would leave the last wire as the ground. The brake output wire is likely going to be a blue wire.

If you do not have a brake controller, then what you can do is use a separate 12-volt battery and carefully touch one of those 2 wires to the positive terminal. Then, in the truck cab where a brake controller plugs in (see video for location) you can test the terminals to see which one has power. Have some one touch and remove the wire slowly but repeatedly from the battery to ensure you have found the correct wire. Once you have found it the last wire is the ground.

expert reply by: Michael H

1