How to test TPMS sensors?
 

I did a search, but is there any way to test them to figure out which one is bad? Or do I systematically have to replace one at a time until the light goes away? I just got some used ones, because I didn't want to have to pull my old ones out when I sell my other rims.

I did a quick check of the workshop manuals and could not find anything either. I have the Harrison CANSCAN with the RX8 enhanced software. With the Harrison, I can read the actual tire pressures for each wheel and the individual TPMS battery strength. To do it you have to have the TPMS installed and initialized to your ECU. Unfortunately, I'm about 3000 miles from you. Maybe someone local from the club can help you out. Otherwise, I guess a trip to the dealer should be able to read them.

I can only talk about the Harrison Scan tool
But that can can pull up what the TPMS sensors are reading. You would have to pull off a wheel to tell which one corresponds to the reading, but once you figure that out you could find the defective one. Now if you can do that at home the dealer can also do that.

Since the Harrison tool (great device) gives the actual tire pressures, you should be able to tell which is which by adding or removing a little air from each tire in turn.

Unfortunately, I'm also on the other side of the country from you.

This could be your excuse to buy a scan tool like this. Systematically swapping wheels, and going through the synching process each time, would be really tedious.

Ken

I have the old version of the harrison scan tool (canzoomer style), and I need to send it back to them to get updated. I tried the re-registration process again this morning and like magic it all works. That was some great info. Thanks!

I've had them go before, usually if you put a film of soapy water (so the moisture stays in place a little better) over each stem and watch for a little while you'll spot the one that is leaking air from the bubbles you'll see forming.

Any updates on how to test TPMS sensors when uninstalled from the wheel?

I figure you could seal them up in a pressurized canister and do a series of tests where you isolate each TPMS out of the canister.... But does anyone have any ideas of what to use for a pressurized canister?

One of those pressurized paint pots without the gun hooked up should work, just plug the air line. Harbor Freight sells them for cheap.

One of those pressurized paint pots without the gun hooked up should work, just plug the air line. Harbor Freight sells them for cheap. Or, a large inline air drier with the filter element removed might have enough space to fit one in.

16 Mph
 

Each wheel unit consists of an internal battery (designed to last up to 10 years), an accelerometer (which turns the wheel unit on over 25 KM/h (16 MPH)), a temperature sensor, a pressure sensor and a radio transmitter
(which sends information to the TPMS control module).

From Bulletin No: 02-004/04
This bulletin shows you how to find a bad sensor.

So putting them in a pressure pot will not work.

Okay the the pressure pot thing will not work to test the TPMS because they don't turn on unless they are spinning at 16mph.

I read the bulletin and still can't figure out how to test them off the car.

May not be posible
 

You will need the Harrison CANSCAN with the RX8 enhanced software or equiv.
Or pay to have a mazda dealer tell you which one it is.

Or at the next SoCalRX meet I can scan it for you.
Ricky & Ronnies (S.E. LOS ANGELES / SOUTHBAY)
IN-N-OUT (ORANGE COUNTY)
but they will have to be installed and mounted.

If your TPMS is not on after you start the car but comes on later............

deflat one tire at a time. The light will come on if its good. Then reinflate and do the next wheel.

Thats a pretty good idea. But normally you have one that is on and never turns off.