i just bought an 09 sierra it had a service tire monitor alarm on when i bought the truck so i made it relearn all the tire sensors by following the owners manual and listening for the horn, i went through the whole process and when i was finished it said all my tire pressures needed to be checked but all my tire pressures are to manufacture specs. my question is that how do i know the sensors are even in the tires would the horn still sound if it wasnt getting a signal from the tires or is it another problem any help would be appreciated thanks

 

The horn would not sound if they were not installed. Are you following the pressure on the door of the truck or the tire?

What are your pressures? Sometimes one can be low by one pound and you will get the warning.

 

Yeah it's I'm going right front left front right back left back then it chirps twice it says 50 in the fronts and 80 in the rears