Guys, what is this button? I bought this truck from my nephew and I don't know what this is.

It is to reset your TPMS sensors after rotating your tires so it knows which sensors are on which part of the truck.

 

Thanks! Dang, I had no idea.

 

No.

That sets the tire pressure NORMAL to your current tires' air pressure. For example: Stock is 35psi. but you decided you want to run 20 pounds while you offroad. That will show on your dash as Low tire pressure. But if you press that button it sets 20psi as your NORMAL pressure, and the light goes out. If your tires then drop some preset percentage BELOW 20, the low pressure light will come on.

 

Assuming you didn't get an Owner's Manual with the truck, here is a legit link (Toyota site) where you can download a free PDF version of all the documents that would have come with the truck.

Not as convenient as the books, but usable.

https://www.toyota.com/owners/resources/warranty-owners-manuals.tacoma.2007

You're welcome.

 

These trucks don't know which wheel is mounted where. The switch is just to set pressure.

 

So it's basically a "TARE" button for your TPMS, but instead of zero'ing, it changes what the "appropriate" PSI is based on whatever your tires are currently?

 

Exactly.

 

Excellent job of explanation fellas.

 

My bad

 

Not exactly right either. It sets the 'normal' pressure to the current tire pressures or to the lowest allowed 'normal' pressure, whichever is greater. I forget the number, but I think it's in the mid-20's on 3rd gens, not sure about 2nd. It does then set a low pressure threshold below that newly set 'normal' pressure.

So unfortunately, you can't zero the system around aired down trail pressures.

 

It definitely worked down to the low 20s on my 2nd gen (usually ran 22-23). I used to take the time to reset when airing down for gravel roads. Never tried when aired down for the sand into the high teens. And I can't go test anymore, one of my sensors died 2 years ago and I'm just living with the light. And after what you stated, I'm not even sure they'd work anymore since I'm usually running 50-60psi now. Might be outside of their range. I tried to do some more digging, but couldn't find anything to definitely say what the lowest "normal" is (on 2nd or 3rd). Thanks for adding more info