Finding Stoplight Circuit for Installing Brake Controller in 2004 Jeep Grand Cherokee

Question:

I just got a response from you guys, thank you for the help, i got another question, what kind of tester did you use? And im gonna send a picture of my wires, I dont think i have a purple and brown wire, i hope you guys can help me again.

asked by: Jorge

Helpful Expert Reply:

We luckily had the chance to install a brake controller in a 2004 Jeep Grand Cherokee just like yours and we found that the cold side of the brake switch wire was purple and brown.

I attached an install video that shows the P2 part # 90885 installed in a 2004 Grand Cherokee just like yours.

expert reply by: Jameson C

click to enlarge

Jorge

6/19/2019

Jameson C.

6/19/2019

The easiest type of circuit tester to use when testing wires for function that won't damage the wiring is a tester like the part # PTW2993 which has a hook end and sharp metal probe that pierces the wire just enough to make contact and not damage it. I attached a picture that makes it easier to visualize what I mean. Sometimes manufacturers change wire colors without warning which is frustrating. Best option is to keep testing the wires till you find a circuit that has 12 volts only when the brake pedal is pressed.