Tire sensor light won't reset.

I have a 2008 Tacoma. Bought from a local dealership, but not a Toyota Dealership. The Low Tire pressure light blinks for a good while and stays on.
I have tried using the button to reset, but it never stops blinking for some time, then it just stays on solid. I have checked the pressure of all the tires as recommended on the tires.
I am new to this vehicle and the Brand. If the dealership changed the original tire size(s), they would have had to get the psi reprogrammed for the new tires?
Any help would be appreciated.
Tires on the vehicle 265/65R17
Tires Listed on the door of the vehicke:
245/75R16
Thanks in Advance
Stu

 

You have a defective sensor.