Anybody recognize this?

This is not in my 09 Taco (that I know of) but in my 20 Tundra. Found it under driver side rear threshold. 1st thought is it's a tracker which it may be but it's in series with the red wire so it's part of the circuit.

 

Did you buy it new?

Anything aftermarket installed like remote start? Aftermarket security?

Looks too small to be a "tracker" but something you could say open the door from 20 feet away.

Can you unplug it and plug the red wire back together?

It's definitely not OEM. Maybe dealer.... in case you missed payments?

If you feel randy you could carefully cut off the shrink tube to see what's inside. Of course you'd want to replace the shrink tube before putting it back.

 

Don't mess with it. If the truck has run fine since 2020 or whenever you got it just leave it alone. If it's a tracker, who cares unless you are going places you ain't supposed to. I have a similar menagerie under my left front kick-panel and a piece with a wire stuck to the windshield up behind the mirror that says "antenna" on it with an arrow pointing up. Very neat installation that hasn't given me any trouble in almost three years/30k miles of ownership. Looks like a remote-start?

I leave it alone, it leaves me alone. So far.

 

I'd look close at the 3 wires coming out of the harness that they connected the black red and yellow wires to, esp the harness wire color. Are they all three the same? Likely at least two of them are the same color and that's where they cut the harness in order to tie it to another wire. Are all 3 (red, yellow and black) tied together under the heat shrink? I'm assuming that's what's under there, could be a flux capacitor though

 

Most likely a brake light flasher. If you stand behind the truck and press on the brakes do the brake lights come on normally or flash fast a few times and then come on? You can take that out just have to reconnect the 2 ends of the OEM red wire and then disconnect the t-tap on the white/black (ground).