Wiring Dome Light and Third Brake Light on a Camper Shell on a 2009 GMC Sierra SLE

Question:

I have a 2009 GMC Sierra SLE Extended Cab. I want to wire in an A.R.E. truck cap that has a CMHSL and a dome light. There is a factory 4 pin flat on the cap. Will this allow me to use the brake light and the dome light?

asked by: Doug P

Expert Reply:

The Curt T-connector # C55384 has a 4-Way flat connector on it. The functions that it carriers are running lights, left turn/brake lights, right turn/brake lights, and ground. If the dome light runs off of the running light circuit and the wiring on the camper shell has a converter that separates out the combined turn signal and brake lights to only include the brake light then this harness will work.

However it is probably not likely that the camper shell is wired this way. If that is the case you can get the CHMSL signal from a wire under the dash on your 2008 GMC Sierra SLE. There should be a tow package wire bundle held together with a white tag. In this bundle there should be an orange wire that is the CHMSL circuit. I have included a picture showing the location of the bundle (under the dash, to the left of the steering column).

You also may be able to get the CHMSL circuit in the wiring harness for the 7-way. You would have to follow the harness up a foot or two, remove the wire loom, and look for a light blue wire. It should show power only when the brake pedal is pressed.

The dome light is a little trickier. If the camper shell dome light has a switch then you could tap into the 12 volt circuit on the trailer connector wiring. But if there is no switch you would need to install one using # PK34513.

expert reply by: Michael H