To clarify how the TPMS sensors work on the Sonic:
When delivered new, the battery powered sensors are attached to the valve stems, inside the wheel/tire assembly with a setscrew. They can be removed from the valve stem assembly, and the valve stem will remain in the wheel. When re-using the sensors or installing them in different wheels, a repair kit is required. The repair kit is simply a new valve stem, valve core, and valve stem cap. The actual sensors' batteries have a service life of ~ 5 to 7 years; then the sensors will have to be replaced, as the batteries are not serviceable.
When the system is functioning properly, the battery powered sensors emit a signal of a specific frequency that is compatible with the vehicle's control module. Each sensor needs to be assigned to a specific location on the vehicle by using an electronic reset trigger activation tool. That is accomplished by placing the driver information center display in the tire learn mode, then starting at the left front, pushing a button on the tool while holding it near the sensor in the wheel, will cause the vehicle horn to sound; then move clockwise around the vehicle, activating the remaining sensors. When complete the horn will sound twice, signalling the tire learn process was successful.
If you rotate the wheels, the sensors will still notify you of a low tire pressure; it just cannot identify the correct wheel position on the vehicle. Some GM vehicles display the actual pressure and wheel position on the (DIC) driver information center. My Silverado and Equinox do this, my Sonic only displays a low tire somewhere on the vehicle; no pressure or wheel position, unless I'm using the Remote Link app and subscribed to OnStar. Then I get this information displayed on my smartphone app.
If new sensors are purchased, they must be the correct radio frequency specific to the vehicle. They also must be activated with the tool, or the low pressure indicator will illuminate, even with the tires inflated to spec.
If you have two sets of wheel/tire assemblies, such as winter and summer specific; they have to again be re-learned when changing from one set to another. I purchased the tool to do the re-learn process because I rotate my own wheels, and have winter wheel/tires that need this procedure done when swapping. I also have three other GM vehicles that I can use the activation tool for. (Note) Older GM vehicles could have the re-learn procedure accomplished by adding or releasing air from each tire instead of requiring an electronic activation tool.
Some dealers will do this re-learn process as a courtesy; others charge varying amounts. I believe a local Tires Plus dealer quotes $5.00 per wheel.
The tool I use is a ATEQ VT15 TPMS Trigger Tool.
I hope that this explanation may clarify how the TPMS system functions on our Sonic's.
opcorn:
