Hey Guys,

While I was out snowblowing (NJ) and trailing my snow gear around with my trailer, I noticed the left blinker starting to freeze solid. The right blinker was working so I thought it was the blinking relay in the fuse panel. I replaced it and the blinker was blinking again.

When I went to do another job, I plugged in the trailer plug
(7 pin plug into 4 pin adapter) and the parking lights didn't come on. Then I noticed only the right brake and blinker worked on the trailer and nothing else.

I tested the plug 4 pin and only the far (4 pin plug --> OOOo) left had 12 volts when the brakes where applied. The far right is the ground.

So I think its the trailer relay that went bad. But I don't know where it is. Can anyone help me on this?

This is a factory trailer wire too.

Thanks
Mike

 

I assume this trailer that you were using is yours & you use all the time?

Usually when you are going to be pulling a trailer you install a HD flasher into both systems.
T/S & hazards.

This pigtail adaptor you are using, is it the usual one?

I need these clarified first.
Btw, if you click the link to my gallery below you will see linlks to differnt things.
One of them is truck to trailer wiring.

 

The only thing harder than troubleshooting electrical is trying to explain it... What year is your rig? Explain, "freeze up." Was it just you turn signal indicator light on steady, or were the LF, LR, and left trailer lights on as well? Is the Bronco working OK, and just the trailer lights are messed up?

Usually, when trailer lights go out,(or act weird, beyond logic), I visually check fuses, bulbs, and grounds on the trailer. Then on the truck I check the wiring under the rear bumper for anything strange. I Make notes on how how things are wired and wiggle things, especially bulbs and ground wires.

Just last week, worked on a '02 F550. Blinkers weren't working. I checked the fuse labeled Brakes/turn signals and it was good. Proceeded to check everything from switch to blinker relay and things looked fine. After a trip to the dealer to look at the scematics, I found that the Main Keyed fuse runs the blinkers and the first fuse just works the brake lights when the key is off.

Truck does not have factory towing, but came with wiring in the back for a plug and the plug under the dash for electric trailer brakes. It didn't have the trailer relay. I just wired it up for trailer. Looks factory, but it's not.

Let me know a few details, at least the year. A lot of times trailers are wired so that one lead is running lights and one is ground. the other two are split up between right and left turn. When you stop it really just lights up both the right and left at the same time.

Scott

 

OK Great Here goes

1. Its my trailer I use all the time.

2. The pig tail adapter is the usual one- ford part

3. It was just the left turn signal that was steady on the truck that I noticed and didn't look at the trailer at the time I replaced the blinker relay.

4. Trailer lights check out fine. I tested the connections with another truck.

5. Truck does not have factory towing but came with the the plug in the rear.

6. No electric brake module up front.

I went to trace the wires from the trailer plug and saw that it runs into factory plugs and then lead to a thick wire lume of wires that lead up into the truck where I can't trace it anymore.

So tomorrow or Sunday I'm going to tap into the wires to see what I can find out.

Any help is greatly appreciated!!
Thanks
Mike

 

Hey I dunno how much help this will be and I may be wrong but it sounds to me like it is more a grounding problem more than anything, maybe make sure your ground to the light itself or the ground wire from the truck isn't slightly broken or something, could be one of the large fuses under the hood on top of the drivers side fender, do what I end up doing most of the time, take it and get it fixed, you can pul your hair out trying to find a problem like this, as simple as it may seem, I know most of the time in the past that has always been my troubles, I have a good friend that builds trailers, so if you do not get it firgured out let me know and I will get in touch with him or email me and I will give you his number so You can contact him, hope you firgure it out, good luck.
Brian

 

It seems funny your trailer checks out ok. The same directional flasher probably runs both right and left, so if the right worked it wasn't the flasher. I'd probably do a visual of the harness from rear to front. Snow or a branch or something MIGHT have ripped something. I've never seen much of a problem with the harness that didn't jump right out at me. Looking at the scematics I have for mid 80's +/- , most everything goes through the turn signal switch. If it was me,(and it has been more than a few times), I'd check bulbs and grounds, front and rear for corrosion and contact. Then check the switch. Might just be a bad turn signal switch.

Again, I don't know what year you have. Find good scematics. I've gone to a few dealerships with clean hands and asked to look at the factory scematics. They've even offered to run copies for me, but usually I can take a note or two and be on my way.

One trick that I do that you might already know.. All my meters have clips on the negitive and I file the points on the positive side down to a needle point. Drawn blood more than once. I can puncture though the covering on the wire without finding the end. This does mess up the seal, so I'm careful on exterior wiring, but it's great for under the dash.

 

The Haynes manaual has great wiring diagrams, and they show the factory trailer wiring.

 

OK Guys,

I found out what it was.

The fuses in the engine compartment were blown. Fuse for the trailer and blinker.

Then after I replaced them, the left blinker was still frozen (trailer plugged in)

Then I inspected the wires in the rear and found that one of the wires were pinched and grounding. So I undid it and everything works great again.

Thanks for your input guys. I appreciate it alot!!!

Mike

 

Firgured it was one of the two,glad ya got it fixed.
Brian

 

It's always something simple and it always takes time. Glad you got it fixed!

Scott