grandicornis

How does the tire pressure monitoring system know which tire is which? Do they use very low range transmitters in each tire with a receiver in each wheel well?

They can't use transmitters that are keyed to each wheel location because that would get messed up as soon as you rotate the tires unless there is someway to reprogram the locations.

???

Stew4HD

I expect that each TPMS receiver at the wheel is addressable to the CPU so that the system can display the location

zroger73

There is a low-frequency, transmitting antenna called an "initiator" near each wheel. One at a time, the keyless access/TPMS control unit sends a LF signal from each initiator. The TPMS sensor closest to that initiator wakes up and sends an unencrypted ID number, tire pressure reading, and temperature (the temperature can only be displayed by the HDS - not the vehicle). This process teaches the KA/TPMS unit the sensor ID's and locations. After that, the sensors broadcast a burst of data every 60 seconds over a higher frequency. After the vehicle is shut off and the wheels are no longer rotating, the sensors go to sleep and stop transmitting.

This is how all of Honda's current direct TPMS's work. Their indirect system measures both individual wheels speeds and the peak resonance frequency of the front tires using the ABS's wheels speed sensors to determine if one or more tires have lost pressure. The PRF measurement was added several years ago to help the system detect a condition when all four tires are equally low.

NooYawkuh

Alls I know is, it's accurate. To the point I couldn't believe what it was telling me when I had a flat on my way home from work today.

I leave work and I just get onto the parkway when the TPMS alarm goes off. I switch to the 4-wheel display and the left rear says 16 psi!! Then it goes to 9 ... 6 ... 4 ... 2 ...

I'm lucky to be coming up on an exit where I immediately pull into a shopping center. MAN, that tire lost all it's air fast!! I don't think I ever got to the rim but I was on the sidewalls for a bit. I can see the wear. Called AAA and they came and put on the temp. There's a small piece of metal tubing on the edge of the tread. Borderline where it may or may not be fixable. Fortunately, I get to a garage near home about 20 minutes before he closes. Pulled the culprit from the tire and plugged it and it seems to be holding air. Small, clean hole. But the fact that the piece of metal was hollow was what caused the tire to go flat so fast. At first, I thought it might have been from one of those 4-prong tire caltrops. Some of them are tubular. But this was too small. I have the piece but I have no idea what it is or what it's from.