Trailer Light Socket

The Jimmy came with the heavy duty trailer towing package, which included a load distributing trailer hitch and a transmission cooler.  It also came with a seven-wire trailer lighting harness that was simply taped to the frame of the truck.  No attempt at making it easy to hook up anything to it, the wires were simply cut off and taped.

I figured the first time I tried to use any of this wiring would be the last time the tape holding it to the frame would actually stick, so I decided to get a trailer light socket.  I went to Pep Boys and found a seven lead socket, which included a mounting bracket.

Well, there are a lot of sport-utes around here, and I started checking out how their light sockets were attached.  Jeep Grand Cherokees apparently come with the socket already mounted.  It's on the outside of the hitch assembly, just to the left of the receiver.  It's mounted horizontally, and has a cover for the back side of the socket.  What's goofy about that is that the wiring goes over the hitch assembly and into the cover for the socket, leaving it exposed for a few inches.

I've also seen several sockets that were mounted on the bottom of the hitch assembly.  I really didn't want that because I'm concerned about ground clearance.  I do some off-roading and the occasional scrape would bust off the socket, exposing the wires which include a heavy lead right to the battery.  I finally decided to mount the socket to the front side of the hitch assembly, flush with the bottom of the square tube.  No ground clearance issues then, unless I actually had the light plug inserted.  In that case, I would probably be towing and wouldn't be going off road anyway.  I had the bracket welded on, and installed the socket as I wanted.  I have a specific truck and a generic connector.  Try as I might, I couldn't find any good standard for wiring the socket, so I ended up this way:

Since I don't own a trailer, I felt that the ideal solution to rented trailer lights would be to connect short color coded wires to the plug, label each one in English, and insulate the ends.  Then when I rented a trailer, the rental shop could put their insulation piercing connectors on the plug wires instead of making holes in the truck harness.

I've rented trailers twice since I installed the socket.  The first time I discovered that the pins on the socket can get out of alignment when you tighten down the screws on the wires, and the plug wouldn't go into the socket!  They ended up putting holes in my harness anyway!  The second thing I discovered is that the hitch receiver is a lousy way to make a ground return connection between the trailer and truck.  When I had the tail lights on, which turned on the markers on the trailer, the markers were flickering almost all the time.

The second time I rented a trailer, I had the alignment issue fixed, but I still hadn't figured out how to ground a trailer that doesn't have a ground lead.  That time, the brake lights, turn signal (same bulbs), and tail lights did work, but were still subject to flickering when the hitch would move in the receiver.

What I'd do different next time

The seven wire plug is still several inches long, and it hangs down quite a ways when it's plugged in.  I would mount the socket in pretty much the same place, but horizontally, with enough room that I could easily plug and unplug the connector.  I've also replaced the ground wire with a piece of 12 gauge and put a big alligator clip on it so I can get a good ground to the trailer.  We'll see how that works next time I have to rent a trailer.

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