am I doing something wrong

Hi gang. New owner of a 2017 Tacoma, TRD Sport. I just bought a Tailgate LED strip with the 4 plug connector attached already.
The only thing that works correctly is the turn signals IF I don't turn on the Headlights. If I turn on the headlights, the signals work as if I have the hazard lights on.
What is going on?
Thanks in advance.

 

Link to what you purchased? How did you plug it in? Typically you need an adapter to go from the vehicle wiring into a 4-pin. Check here: https://www.etrailer.com/t1-2017_Toyota_Tacoma.htm?&Redirect=8

 

I just plugged it into the trailer w/h plug. This is the strip I bought.

$29 KYYET Arrow 60" 528LED Truck Tailgate Light Bar Strip RED Brake Sequential Amber Turn Signal Strobe Lights

https://www.amazon.ca/gp/product/B08RBS16VT/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

That product got a lot of bad reviews. Maybe yours is defective?

 

Looking at the reviews it doesn't appear to be anything you did wrong. The Taco is VERY picking when it comes
to brake and turn signal circuit resistance values. The fact that the strip changes behavior when you turn on the headlights
is another clue that it is probably never going to work properly.

 

I actually think it is the truck. This is the 2nd strip I bought. The first one didn't come with the connector. I bought one separate and hooked it up. It did the same thing.
Perhaps I'll send this one back and give up.
Did anyone else have the same problems, or is it just me?

 

No problems here, but I just did a straight taillight. Turns and running lights are overcomplicating things, and will only serve to confuse folks behind you (especially running lights). My humble ignorant opinion.

One question. What's your other, regular taillight situation? Completely 100% incandescent stock, or did you swap some LED bulbs in there? Are they working with the strip unplugged?

The truck shouldn't be sensitive to the trailer connection resistance, since those are variable as hell. But it is highly sensitive to the resistance of it's own tail connections.

 

The signal lights have been changed to LED. They work fine. The stop bulbs are still stock, incandescant.

 

Get a tester for the 4 pin towing connector, you might have a bad turn wire and/or bad towing relay trace.

 

In a former life I ran a landscape construction company and had a combination of Isuzu (Japanese) and Ford/International (American) trucks. Whenever I was rewriting a truck or trailer, the Japanese trucks required an adapter to split the stop/tail/turn signals. Your problem sounds similar to this but not exactly. I wonder if there is an issue with the light strip or if it is made for American style wiring.

https://www.buyersproducts.com/product/heavy-duty-tail-light-converter-248

 

I don't know what a "w/h plug" is but I'm assuming your truck came with the tow package and you are plugging it in to that. Unless someone messed with the wiring, I doubt it's the truck. As the other posts mentioned, get a tester, or try a different brand strip.