Trying to understand TPMS Sensors

zelmo · May 5, 2020

I got the sensors installed on my single axle trailer and hooked it up to the truck. I had already attached the trailer before and saved a profile so all I had to do was learn the sensors.

I don't have a tool so I had to do the pressure change routine. With the truck running I entered the program in the trailer app. and selected single axle. I had everything ready so I proceeded to let the air out of the first tire. I dropped it by 15 lbs (with a very accurate gauge) and never got the horn beep or lights flashing so I went and looked at the screen. The tire I had worked on had the green check beside it and it was counting down on the second tire. I went back to it and dropped the pressure 15 lbs, again never getting the horn or flashing lights. I went back to the truck and it said that tire had been learned also.

Then I checked the pressure. The first tire listed the pressure at which I had started and the second tire had the pressure at the level I had dropped it to. I then turned the truck off and filled the tires to the proper pressure and when I started back up both tires listed the low pressure. I was going to try again but when I selected the setting for that it told me the sensors had already been learned. On a hunch I decided to drive around the block and within a short distance both tires were showing the correct pressure.

Any ideas what is going on and more importantly can I trust these readings?

steve841 · May 6, 2020

It's not an instantaneous readout from the TPMS especially if you're not rolling.

I had the same issue with one set. But started the process over and got it all setup.

Sounds to me like you are good to go.

Edited May 6, 2020 by steve841

zelmo · May 6, 2020

11 hours ago, steve841 said:

It's not an instantaneous readout from the TPMS especially if you're not rolling.

I was hoping to get an accurate reading before pulling out of the garage in case the tires need to be topped off. That means I'll still need to check them with the gauge.

I think what I will do is lower the pressure in one tire by about 5 lbs and go for a drive to see how long it actually takes to update.