Good evening everyone,
Today I installed trailer wiring on my van, and it was a little different than usual because I needed power for the reverse light circuit at the plug. My boat trailer has hydraulic surge brakes, which makes it virtually impossible to back up without power to that pin. It took a good bit of digging through the shop manual to find the best place to tap the reverse light circuit, so I figured I'd post this for anyone else with similar needs.
I started off with the installation of the 4-pin kit I got from eTrailer. This was the one I used, but I imagine most of them install the same:
For the 7-pin plug, I chose this Pollak kit from Amazon. Pollak is the OEM supplier for Ford, GM, Chrysler, and virtually every other vehicle I've seen that offers a factory plug. This is better quality stuff than the 4-to-7-pin adapters from Curt, Tekonsha, etc., and I highly recommend it.
The design of the Pacifica made this the most challenging install I've done, and I wouldn't have wanted to do this without a fish tape. You have to pull the tail lights and fish the connectors up between the bumper cover and the guts beneath, which was more than a little challenging. Running the wire to the battery was relatively easy because of all the underbody shields you can string it under.
As we all know, the reverse lights are in the tailgate, so I had to locate the wire in the left-side harness at a convenient location. Behind the driver's side D-pillar trim was the easiest. The panel snaps off, but you have to be careful with the power tailgate switch(if equipped) and a very interesting fastener directly above it. It snaps off, but there's a retaining strap for some reason that unclips once the panel is loose.
Using a knife I cut away the cord wrapping for about four inches to expose the wires. The left-side reverse light is powered by the beige and white wire in this bundle, and I tapped it with a suitcase connector.
Getting the wire to the exterior was relatively simple when I located this rubber grommet. It's behind the spare tire, you just have to pull back the sound insulation. I had to pop out the adjacent vent and use a fish wire to get the wire below the bumper.
I connected the lighting circuits of the plug to the outputs from the Tekonsha unit after clipping off the 4-pin end. I spliced the power wire to the one I ran for the light module, and the reverse circuit from the wire I ran in the photos above. Overall it cleaned up well, and here's the final product before installing the diffuser panel:
Hooked it all up and went for a test run with the trailer. The Pacifica handles my 3,500-lb boat really well, I'm quite impressed.