STS134 wrote:The sensors actually measure pressure. And the transmitters transmit pressure (as well as temperature). The system uses FSK modulation and 100 kHz bandwidth to transmit its data at either 315 MHz or 433 MHz. http://i56578-swl.blogspot.com/2017/08/ ... -tpms.html
The threshold is set based on the tyre pressure which the reset function is executed by following procedure.
1. Operate the multi-information display switch to switch the information screen to the menu screen.
2. Lightly press the multi-information display switch to select “ ” (reset of low tyre pressure warning threshold).
3. Hold down the multi-information display switch for about 3 seconds or more, the buzzer sounds.
4. The warning lamp start flashing slowly.
5. Drive for a while. The reset is completed if the warning lamp goes out.
I presume (it's not clear from the text), that this will reset the threshold as a set amount below whatever the pressure in the tyres is when this reset procedure is done. If that makes any sense? So the sensors must be transmitting a value that the software interprets as a "starting point" for the warning function. You can't actually set a value of pressure, just a base point, from which the software calculates pressure drop. I've never fiddled with this, so I can't say whether this is actually how it works or not.
Regards, Ray. 2014 GX4H Glacier blue.
It's the 21st century - so where's my nuclear-powered flying car, then?
I regularly check and amend my tyre pressure, however due to commitments I have not check the pressure since the end of September. Front tyre down to 28 psi rear down to 33psi (Rear tyre pressure normally set to 38 psi due to carrying a heavy Motability scooter), I don't have the confidence or ability to mess with the tyre menu settings so I brought one of these, I have an older version on our caravan for the last 6 years it simple/ easy and extremely accurate.
I decide to buy one off these £98.00 including my discount, easy to set up just fit the sensors in place of the tyre valve cap and the system does the rest, I now can monitor both the tyre pressure and temperatures.
I fitted internal tyre pressure and temperature sensors to mine.
(A little solar powered unit on the dashboard gives a constant display of temperature and pressure for each tyre while the car is in motion, or if you press a button on the side of the dashboard unit.)
I had the steelmate valve top type for a while and found them to be excellent, they gave me early warning of a slow leak which meant that the tyre could be repaired before the tek screw had done too much damage.
I only replaced them because I was sick of removing them every time I wanted to put air in the tyres.
2014 PHEV Aspire, Arctic Silver;
Hayman Reese removable tow bar;
1.5kW Solar, grid connected.