Buggy, any chance you can provide a picture of how you spliced into your wiring? I have a 2014 and I spliced into mine without any issue. I cut and soldered my connections. I can't see the 2015 being any different as far as connections are concerned. What type of Light bar do you have?

 

I installed a putco blade bar on my 15 and it came with instructions on jumping a wire under the dash to keep it from saying that a trailer was connected. Can’t remember the exact location. I’d have to crawl under and check

 

I just installed my Putco 60' blade to my F-150 2016 Lariat with Bliss. Below is how i wired them and I'm not getting any alert on my dash that trailer is connected. The only issue I experienced is the color of the wires varies.

Here’s how I wired them.
- Using the harness, I cut the red wire as instructed and pulled it out (see link for instruction below)
- I cut the four wires from the harness (black, brown, yellow, and green)
- I fed the black (ground), brown (running light), and yellow (left turn signal) to the driver side tailgate housing and fed green (right turn signal) to the passenger side tailgate housing
- NOTE: the tailgate wire colors are not matching with the harness wire color
- I spliced the black harness wire to pin 1 wire (ground)
- I spliced the brown harness wire to pin 4 wire (running)
- I spliced the yellow wire to pin 10 wire (turn signal); same with green wire to pin 10 wire on passenger side (right turn signal)
- I ran the white and red wire to the tow hook and spliced red wire to orange wire (aux 12V+) on 7 pin connector and white wire to the center wire (back up light) on the 7 pin connector
- I installed the bridge to the passenger side dash by splicing the red to the orange wire and the other end of the red wire to green/red (see p. 4 from the installation instruction - link below)

Installation instructions can be found here

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2016 F-150 Lariat Shadow Black
Modifications:
BAK BakFlip MX4 Tonneau cover
K&N intake
Borla S type black tip split rear exit catback
Stubby antenna
Catch Can - UPR Dual Valve
Rough Country Heavy Duty LED front bumper (with light bar and cube fog lights) and rear bumper (with cube fog lights)
PUTCO Switchblade LED Tailgate Light Bar

 

Pull your battery for 20 minutes to reset the computer. I had the same problem for 2 years until I had to replace my battery. Battery was off the truck for 10-20 minutes, now I have all my backup features back and it doesn't thin there's a trailer attached anymore.