Factory Trailer Wiring connectors

[Waldo21]

Hello all. Well this is my first post here as I'm the proud owner of new-to-me '90 F250 4x4, Extended cab,7.3 IDI. To make a long story short, I'm trying to sort out a mess of trailer wiring.

There are three things that are thwarting my efforts at successfully hooking up a 7-pin connector. I'll start by saying that this truck appears to be factory wired for a trailer but through the years of previous owner mods I'm not sure what was done at the factory and what was done by Joe Mechanic. (One of the previous owners carried a camper and there is bundle of severed wires remaining from that - yay)

I currently get the turn/brake light signals at the back plug but no reverse, power or marker. After studying the Haynes wiring diagram I noticed that there should be a marker light relay. After hunting around (and I mean hunting because I'm partially color blind + the wires are all dirty) I found the 5-pin female connector coming from the harness that should go to a relay. The question is, where is the relay supposed to be? Assuming that this was never there/isn't there, does any one know the part number of the male connector? The female portion has two horizontal blades on the left side, one larger vertical one on the top right, and two smaller pins on the bottom right (combined these last two look like one large vertical with a separator in the middle). Only 4 of the 5 are used: relay power, ground, signal (from light), and switch leg (to trailer marker lights).

The next issue is the brake controller wiring; After researching the posts in this forum I have found the little round gray plug at the bottom of the firewall that is for a brake controller. Two questions: does anyone know of the part number or where I can get the male end? There are three wires in this plug: power, a blue one that runs to the back for the trailer brakes, and a third striped one that I would assume should be the brake signal? This wire is always dead for me. One of the previous owners, for whatever reason , decided that he didn't like the ABS in this truck and had a brake shop bypass the ABS valve. [img]/ubbthreads/images/graemlins/shrug.gif[/img] Could this be why the stripe wire gets no signal? If anyone else could verify on a stock truck that the stripe wire gets power when the brakes are on I would very much appreciate it. I know that I can tap into the light green wire on the crescent shaped connector for this purpose but I would rather keep this install clean.

The last issue is the reverse lights. Is there supposed to be a reverse light wire on the trailer plug for these trucks? If so mine never gets enabled.

[Waldo21]

Well I sorted out the issue with regards to the marker light relay. It turns out that it is just a general purpose relay that plugs right onto the end.

One down, two to go.

[cdnsarguy]

Check out....... http://67.18.170.154/home/wiring.asp

Mine is a 93 so we have the engine compartment fuse box which handles the trailer.

[Willie]

check your PM box