TPMS alarm

[padlin]

This is not camper related.

Got a slow leak on the car a few weeks back, the tire shop found a piece of a razor blade in it that I'll blame on going to the town dump, which they plugged. It seems to hold air just fine but I've had a couple pressure alarms in the car since then. Both times it was after 3 or 4 hours on the highway. Both times I pulled over and checked the pressure, the 1st time the tire read 53 psi, which was about the same as anther I checked, this being on a 90 degree day. The next time it was about 70 degrees out and the tire read 35 psi, maybe 2 psi less then another one I compared it to, spec for the car is 30 psi.

Any idea what gives here, maybe a battery? The car is 10 years old, tires are 2 years old and have less then 30k on them. I can't really tell which tire is causing the alarm, I'm just guessing it's the one that had the leak.

After stopping, turning off the car, checking the tires, then restarting, the alarms went away, not to return for a couple weeks...

[Brian B-P]

Do you know if this TPMS is based on sensors mounted inside the wheels, or is based only on the rotational speeds of the wheels? Speed-based systems just look for one wheel turning faster than the others, averaged over enough time to cancel out the effects of turning corners.

[padlin]

It's a 2009 Corolla. Looks like I can buy replacement tpms sensors for inside the wheels. While looking for that I found I can reset the system with a little hidden button I didn't know existed. Once it stops raining I'll set all the tires and try the reset. Thanks for getting me looking.

I am/was surprised to find the tire pressure all the way up into the 50's, a lot higher then I would have imagined.