7 Pin Problem

Bringing this thread back for a conclusion.

Like others have stated, I was leaning toward a trailer wiring issue. I too, several years ago, had a wire rubbed raw and it was causing problems. But at the same time, one would think that would blow a fuse.

I finally got a chance the other day to start looking around. Took the 7-pin apart and it looked perfect. Crawled under the trailer and looked over all the wiring that was not harnessed. Then starting pulling wheels. The second wheel I pulled, I noticed a wire hanging loose and another wire with a connector on the end hanging loose. They weren't really close to one another but the fact that both were just hanging there and a connector was on one threw up a red flag. So I had my son get in the truck and with 1. nothing, 2. parking lights on, 3. and then with the brakes applied, I would hold the wires together. I figured I'd blow a fuse if it was a problem. Nothing happened.

I stripped the ends, got another connector, and put them back together. The problem has not occurred since. My guess is this was a ground wire and it was giving me intermittent ground. The brakes work better as well and I think that's because I only had brakes on the left side before the break in the wire. But these are both guesses.

Any way, problem solved. Thanks to all.

It's pretty difficult to troubleshoot wiring problems on vehicles sometimes. All the suggestions thus far are very good ones.

Once the op determines if it is the tow vehicle or the trailer using a test plug that has been mentioned, then checking all the wiring for shorts or loose connections. Hopefully the op's problem will be a simple plug problem, and not have to resort to total rewire of the trailer like I had to do.

My particular fifth wheel ended up being the wires on the trailer, where they actually are routed through the axles to the brakes on the side opposite the harness. The wires had chafed and shorted to the axles intermittently causing the errors very similar the the op's experience. I ended up replacing the entire harness with heavier gauge wires which were recommended by many who had similar issues. It seems that manufacturers sometimes don't use heavy enough gauge wires in the brake harnesses, probably to save money. I also did not route the wires through the axles as the manufacturer had done. I strapped the wires to the outside of the axles and I used 12 gauge extension cord which has thick insulation to prevent shorting in the future.

There are several threads with photos showing how to do all this.

WyoTraveler wrote:
That connector has a module that can be replaced. ... Just pop out connector module and put in a new one. 5 min job. I would try a contact cleaner first.

How did you do that? I looked at mine and did not see how it comes apart. Did you get the module at a Ford dealership or somewhere else?

Thanks!

Used to happen to me until I used a tie-wrap to hold the plug tight to the open plug cover. Just wrap it around the cover and plug. On mine the integrated brake pin was on top when plugged in and it used to wiggle out ever so slightly. Haven't had a problem since I've been tieing it.

Had a similar problem. Checked all the connections and they were good. finally pulled the wheels and hubs and found one of the wires inside the wheel had chaffed and was intermittently grounding. Fixed that issue and it never happened again

camperkilgore wrote:
I bought one of these to help troubleshoot connection problems.
http://www.amazon.com/Tekonsha-6562-Trailer-Emulator-Display/dp/B004BCA9B8/ref=sr_1_2?ie=UTF8&qid=1461111153&sr=8-2&keywords=trailer+tester+7+pin

I prefer this one since it is both a 7 way and a 4 way tester.

Bad ground on trailer can cause this too.

When I assemble umbilical cables, I always solder the end of each wire and then insert into the plug. It makes for a better contact, screws are less likely to back out.

Most problems are on the truck connectors or the trailer plugs, after a few connections and disconnections the little screws come loose and the wires pull out, when I instal new connectors I twist the wires and add a dab of solder, this alaws me to tighten the small screw pretty tight.

There is a product sold at Home Despot that is liquid tape, I use this to seal the connectors where the wires are attached so that no water or moisture gets there, I also use electricians tape to seal where the wire cable enters the connectos and the sockets.

If the sockets or receptacles get damaged I eplace them, wigling the plugs also widens the round female ends and that can cause an intermittent connection.

navegator

I like to squirt some WD40 into my connectors and wiggle them around good... We all probably got a squirt can of WD40 in the side pocket anyway along with a roll of duct tape...

Roy Ken