running lights ok but no brake or turn signals

I'm glad you got it straightened out and under warranty, makes it nicer yet!
Happy camping!

Took it to the dealer....under warranty. Loose module was what they found...and it took them a long time...they were checking everything...electrical issues can be tough to find sometimes.

Had the same thing happen once, it was the trailer fuses on the truck. I was away and used some fuses I knew I didn't need at the time (seat heaters etc.) The only thing I found that may have caused this was the under bumper 7-way plug got water in it driving in heavy rain while we were not towing? I sealed up the back side of the plug and never had another problem.

DSteiner51 wrote:

irbf30 wrote:
Plugging in truck and starting while trailer is plugged in to shore power will blow this fuse. Don't ask me how I know this.

Hummm? I do it all the time.

DSteiner51 after looking at your older tow rig in your pic I can understand why, besides..... I'm not too sure where you would find the fuse box :h

Was gone over the weekend. I bought one of those 7 pin testers and the plug is dead for the brake and turn lights. I am going to look into the book and see if the info Bipeflier will work for me. I was hoping someone knew exactly what fuse to check on a 2016 Superduty.

Allworth wrote:
I know! I know! GM trucks are different...but...

My Chevy has separate fuses for the trailer lights (Running; L-Turn; R-turn; Backup) in an small fuse box on the driver's side kick panel behind the parking brake pedal. PITA to get to and even harder to read the call-outs.

^^^^^^^^^^^Yep-Reason I also posted this but did not know if OP's truck had one. Happened a couple of times so I now carry a few spares of every size. There is also a few spare fuses in that location.

Campinfan wrote:
nothing in the manual mentions the trailer brake or stop lights. The closest I see is Trailer Tow park lamps but those are working. I have lights when I turn on the lights just not brake or turn signal.

Without going into the fuse panel and where or how to find the fuse, if you plug your trailer connection tester into your truck socket, does it test good? Yes, then it's in the trailer wiring. If it tests bad, then find the fuse panel that has the turn signal fuse(s) and using you DMM check the fuse. No power check the flasher, power through the fuse, check the wiring from the fuse to the truck socket.

On my '97 F150 there are actually three fuse blocks to be checked, under the dash, two, side by side on the left inner side of the fender under the hood.

I know! I know! GM trucks are different...but...

My Chevy has separate fuses for the trailer lights (Running; L-Turn; R-turn; Backup) in an small fuse box on the driver's side kick panel behind the parking brake pedal. PITA to get to and even harder to read the call-outs.

From another board:

it is all in the owner's manual under roadside emergencies.

pg 333:
fuse 37 pass fuse box = trailer brake control

pg334:
relay 6 underhood = trailer park lamps
relay 9 underhood = TT battery charge relay
fuse 17 underhood - trailer brake control
fuse 37 underhood - trailer left stop turn relay
ect ect ect

check out fuse 67 under hood listed as TT park lame relay power.
and fuse 73 underhood listed as TT stop/turn lamp relay power

looks like they are using a couple fused circuts to power a couple relays for TT wires.

Trucks do have separate fuses for the trailers lights and power.