I installed a Putco Switchbalde LED tailgate lightbar on my 2016 F-150 (aluminum body). Everything works, but I keep getting messages on the display that include.....
trailer connected ... trailer disconnected ... turn signal bulb fault.

This is connected to the stock 4-pin trailer light connector. Has anyone run into this problem? My thought is that I need to run another ground wire directly to the ground wire on the lightbar

 

It thinks your hooked up to a trailer as long as your plugged in to the 4pin.

 

it is not just f150 , my f350 has the same warnings, Putco has no answers for mine, febuary for the f150 correction.,

 

The F-150s "look" for an electrical signal back there to detect a trailer being hooked up for the features of the truck. Plugging a light into that connection makes the electrical loop and fools the truck into thinking a trailer is hooked up.

I would connect the wiring into the tail lights instead.

 

Did you get the new style light bar installed? I did and the new one still has problems. There are no more trailer warnings, but if you turn the lights on, apply the brakes and then use a turn signal, the bar malfunctions. The bar directional signal only works occasionally and if you step on the brake at just the right moment when the signal is on, you can get the bar directional signal to flash in the wrong direction. I thought the bar I had was defective, so I had my installer replace it. The new bar does the exact same thing. Putco obviously has a defective design. It's too bad, because other than this defect, I really like the bar.

 

Hmmm...sounds like the new CAN BUS electrical architecture of the trucks isn't communicating well with the internals of the LED light bar. Trucks now days are rolling computers...it's hard to diagnose these issues sometimes. Each wire on the vehicle has multiple functions, so tapping into a wire can cause odd side effects.

 

As others hinted at... it's because you are using the trailer harness to power the light bar... big no no (well not a BIG no no but it's a no-no).

First... you have something plugged into the harness. It knows this. So naturally it thinks you have a trailer connected. Even if the warning goes away it will THINK you have a trailer connected... that means the reverse backup sensors will be disabled at all times.

Second... you could fix the message from poping up all the time if you used a Load Resistor (trailers have amperage the computers looking for, as it's powering taillights on the trailer... that LED bar has almost no amperage since it's LEDs) but again, even if you do that, see issue #1 with the reverse sensors.

The right way to do it is use a relay and tap off the various lights on both sides. It's a lot more work of course BUT it's the right way to do it and your computer will thank you for it.