To get started, I purchased a Travel Trailer (May) and I couldn't figure out why my backup camera didn't work. I finally figured out that the running lights are not working of the 7-pin wiring harness.
It was kind of interesting to learn why those runnings lights are important which tells information about the trailer.
The truck is a 2018 f150 platinum with 5.0L.

I'll list a few things that I know and I've done:
- Purchased a 7-Way Trailer Light Circuit Connector Tester which confirmed my problem
- I tested the travel trailer by jamming a 10a fuse between 2 pins and the trailer running lights and camera are working
- I replaced the Trailer tow park lamps fuse 53 - it was not blown.
- I tested the voltage on the brown wire harness located near the steering column. 14v while engine is running and running lights turned on.
- It seems like the same problem occurs for the 4-wire harness (was expected)
- Important note: A rodent ate through my wiring harness and fuel line earlier this year (January). It has been replaced by the dealership ($$$$$$). That was before I noticed the problem.

My next steps:
- Trace and test wiring from the steering column to the back
- Bring the truck to the dealership - maybe the wiring harness replacement caused the issue ???

Any other ideas on what should be checked?

 

I have a 2018 5L.
When the Trailer is plugged in, either the 4-wire connector or through an adapter to the 7-lead connector, all that is lost with the Camera are the guidelines because they have no use after a trailer is hooked up.
Also, the auto stop start is disabled as it has no function with a trailer connected.
All the Camera is for at that point is allowing you to back up and align the hitch and ball and use the + Magnification Display to see more closely.
It appears the wiring is still damaged at some point.
The Tow electronics detects the Trailer lighting to ground and inhibits these functions.
Just inserting a 4-wire test plug will to the same thing.
A test plug is usually less the $5 and may be helpful in seeing the leads in trouble.
Good luck.

 

After figuring out how to lower the spare time (everybody should at least try once, my key didn't work since it was seized), I think I found why it's not working.

A brown wire is cut and I'm trying to figure out where it is suppose to go. Of course it started raining.


Right over the spare tire - wire is cut.

 

my guess is someone took the tailgate off without unplugging the wire harness near the spare tire.

 

Took a much better picture and now I see where that goes. Seems like that could be rodent damage.

 

Found some terminals at Autozone (not exact match). But it will work for now. Tester now shows running lights on.

Ford dealer didn't have the terminal part. I would needed to change the whole harness ($$$).

Fixed for $4.50 (package was open). Dorman 85347. Again, fit isn't perfect.

 

If you have future problems and want the correct terminals they are as follows:

Large female are TE 1326032-4 or 1-1323032-0
Small female are Molex 33012-2003 or 33012-3003
Large male are TE 1326031-4
Small male are Molex 33000-0003 or 33000-1003

The large seal is a Yazaki 7158-3112-70 if that is damaged.

 

Sorry, deleted post. This was meant for another thread. Don't know how it ended up here.

 

Thank you! TE 1326031-4 is exactly what I need. Searched for hours.

I'm not happy about what I've done (but it works). So I'll order the right piece and redo it.