Installing New 7pin plug and ALL trailer lights flash!

[Red Horse]

Guys,
I was hooking up my Pequea trailer to my '23 F-150 and got a "Trailer Brake Module Fault" on my screen.."Trailer not Connected". I was pulling my 4720 Cab with loaded tires, 400-500 lb weight block plus a set of forks in addition to the bucket as the load and did not want to trust my 150 without trailer brakes. So one of the guys comes over to pull it with his 5500 Ram and everything worked! Then someone towed it with a 2500 Ram and another guy used it with an F-350. Everything worked!

So take it to Ford dealer and they say not a problem with truck..in spite of screen message..and this is a factory tow package. So given fact lights worked when 3 other trucks pulled it I was sure it was the truck but in anycase I pulled the trailer plug apart and could not believe..it was packed with fine silt/mud! No clue how lights worked with other trucks but in any case I bought a new plug. I'm sure I hooked everything up correctly to new plug, but when I test it with Hazards, every light on trailer is flashing. Likewise when I test turn signals, every light flashes. Turn just lights on, no problem, lights work without flashing.


Any suggestions? Friend of mine says its a ground problem but I say if so, why would everything flash when using turnsignals or hazards???

 

[mrmikey]

I was going to say ground also LOL.
Did you try your truck on another trailer?

 

[Roadworthy]

Disassemble your new connector looking carefully for any hair fine wire strands that may be jumping between a couple of pins.

 

[Red Pepper]

Ground Problem is likely your fix. The circuit needs that return to source, otherwise it finds a way on its own.

 

[Red Horse]

I was going to say ground also LOL.
Did you try your truck on another trailer?

yes works fine.

 

[Red Horse]

Disassemble your new connector looking carefully for any hair fine wire strands that may be jumping between a couple of pins.

thx-good thought

 

[nisaacs]

Sounds like a bad ground, the signals are using the other lights as a ground and lighting up. Pull the trailer off the ball and see if you have any lights at all. If not, then you have no ground from the truck.

 

[Red Horse]

Guys,

thx for all the responses.sounds like for sure everyone thinks it is a ground problem.

One thing I did today was pull a side marker light that was out. Tested leads to light and they were hot. Then I noticed license plate light was out..for good reason -wires were disconnected and light was good.
But what reason, all the marker lights were no longer flashing when I put hazards on!

Then I tried all the combinations and recorded in a message on my phone what each activity resulted. And then in a typical old geezer move when I tried to open on my Mac Book, I lost it.

One thing of note, after I separated truck from trailer, I hooked up a test box that has the same small battery that you typically have as a break away power source. All markers were flashing when rt or left turn signal operating.

I'll run the same cycle of test tomorrow with truck hooked up and hopefully I wont lose results this time