Which Wire in Factory 7-Way Harness Carries Brake Signal and Turn & Tail Light Signals

Question:

Which wire in the factory harness comes from brake control at rear of truck 2008 / 3500

asked by: Chuck

Expert Reply:

The usual wiring color/function configuration in an OEM 7-way harness can be seen in the included photo of a 7-way vehicle socket. An article on wiring is also linked for you as a guide.

The socket pin at 5-o-clock carries the brake controller output signal for the trailer and this is usually routed through a blue wire. This blue wire leads from the blue wire on the quick-connect brake controller harness you referenced, part # 3021-P. Stop/turn signals are usually carried on the yellow (left) and green (right) wires that lead to the 9- and 3-o-clock socket pins on the 7-way. Running light signals are usually carried on a brown wire that leads to the pin at the 11-o-clock position.

Different wire colors can sometimes be substituted at the time of vehicle manufacture, so it is always "best to test" by using a circuit tester such as # PTW2993 while a helper activates each electrical function on the truck. Testing removes all doubt about what wire does what.

For reference I have linked our page showing all replacement 7-way harnesses for your 2008 Dodge Ram.

expert reply by: Adam R