For those that like odd problems

In another post last fall I reported the brake lights were on all the time. No one had a clue as to why. I replace the brake light switch and tested with another TPMS from a junkyard. Problem not fixed.

When certain it was somewhere in the wiring I tested with a Power Probe ECT3000. It puts a signal into a circuit through the fuse for a circuit and uses a receiver to pick up the signal and indicates if its a short or an open.

In the back of KK with the factory tow package is a bundle of wires and three relays that control the regular brake lights and the center brake light. The ECT3000 told me there was an open there. After I cut open the taped bundle and looked for a broken wire and found nothing, I pulled on the bundle and behide a foam insert. There between the bumper cover and sheet metal of the real quarter panel were three relays bound with electrical tape.

When the bundle was free the brake light on problem disappeared. The cause was some jerk engineer or factory worker placed the bundle between the sheet metal and the bumper cover. I don't know if they are all that way or not. What happened with mine is I was towing a trailer in the national forest and and had to back up to turn around. For those that tow you know that a short single axle trailer is hard to back up on uneven rutted ground. In my case the tongue made contact with the bumper cover and pinched the relay bundle. Pulling the bundle out relieved pressure the pinched relay.

Testing the relays with a a Relay Buddy showed one was not operating. (Stuck in an Open position I assume). Jeep wants $30 for the relay. I got 5 off ebay for $13.

Why they used three relays in this package is beyond me. There are two brake light circuits in the KK. Pulling fuse M1 extinguished the brake lights and allowed them to operate normally without the center brake light operating. And somehow, this design with a bad relay also caused no power going to trailer brakes which are on another circuit all together. I assume its somehow related to programming in the TPMS.