Had a test of the Tire pressure sensor today. As I made my way out of the shopping center today the low tire pressure indicator light and message center said low tire pressure. I got out and looked and did not notice any thing. I thought "oh great, now that thing has went crazy". When I got back to the Condo, I checked each tire and the right rear had 18 psi. Got to looking and found a one inch sheet rock screw stuck in the tire.
Fixed it on the SUV with out removing the tire, with a tire repair kit I always carry. Pumped it back up to 35 psi with my 12 volt compressor. The TPS light was still on, but went out after driving it about a mile. So I guess it really works.
By the way I tried my old trusty "let go of the steering wheel low pressure tire test" to see if I could tell if I had a low tire, but did not notice anything. Usually a tire has to go real low or be going at a higher speed than 35 for this test to work.

 

I just got a screw in my tire and the sensor kicked up a lite. Tire was at 20lbs pressure. Hard to tell looking at it. Now I hope the screw is not too close to the sidewall so it can't be repaired.