TPMS light after bedding brakes
 

Howdy,

Just got my AP Racing Sprint BBK installed last night and went out on a bedding run a bit ago. After the run while doing cooldown on my way to park, the TPMS light came on and is persistent (not flashing), even after parking for a bit and shutting the car off.

Tires, wheels, and TPMS sensors are all new. Sensors are OEM and we’re tested on the vehicle before I took the wheels off for the brake install. Any thoughts as to what would cause this?

No codes shown on a scan tool, so as far as I can tell it’s specific to the TPMS system.

Low tire pressure?

I can imagine that tracking may rise pressure too much .. but just bedding? So far only case that something light brake related on dash (except slip light if with nannies on), was red handbrake sign, when during track day pads worn down so much for fluid level to fall below min. Some extra fluid to normal level, and that indicator shut off for good.
Does TPMS measure / indicates on twins absolute pressure or only difference between wheel pressures to indicate some underinflated/overinflated/punctured tire? As my is early 2014', i don't have TPMS installed, which i guess simplifies things usability side.
Theoretically heavy braking for bedding may heat front brakes/tires more then rears due weight shift when braking, so maybe that might be the reason of detected pressure difference. I didn't thought that it would be enough pressure difference to trigger TPMS though.

I was pretty stout on it when bedding. I already verified tire pressures were even and within the correct window (35 psi cold, under 38 hot). I checked the pressures as soon as I parked, then I checked after waiting an hour for a full cool down of brakes/tires. Everything checks out functionally that I can tell, which is why I’m confused. Best guess is maybe I need a reset because I had the wheels off when doing the brake install? But the light didn’t kick on till the tail end of my bedding run.

What’s the usual thing to do if this happens on the track? Just reset TPMS with a tool?

Check out the front TPMS sensor connections. Maybe some sparks shot out of your brakes and shorted one of them.

Check tire pressure the old fashioned way and ignore the stupid light.

Remember that the light goes on for only two reasons, tire presser is out side of what the factory wants and programing the units. Many have been fooled by a light on after thinking the programing is good, there is a lag time before it comes on, or having old tires near the car with the units still programed.




Ok, one other thing, bad units.

Sounds like maybe they weren't programmed properly at the tire shop... Oh well, I guess I'm living with the light until I need new tires. Good motivation to go hoon at the track again. It's weird it didn't kick on until weeks after I had new tires put on originally. But there we are. Pressures are definitely good, and I don't think a sensor failed because they're new OEM parts.

If I needed to test for whether the sensor was working, what sort of tool would I need?

Sensors are in the wheels with no physical wiring connections to the car.

Do you park near the original wheels/sensors? What's the longest drive you've made since installing the new wheels? You have to drive ~40km's before the light will come on. I don't have sensors in my winter wheels, but the car reads the sensors from the summer tires in the basement as long as I park in the garage. On drives under the ~40km mark I don't get a light at all, even though the sensors are no where near the car.

As for programming, that can be done without removing the tires... no need to wait for the tires to be off.

My understanding is that SN of the TPMS sensor has to be programmed into the ECU, it’s not sufficient to put the car into a learning mode and simply drive. Is that incorrect?

^^ Yes, but from what I've read, most tools that can program it can also read which sensors are nearby and then set them in the ECU. There is definitely no learning mode though.

Fun update. The TPMS light is back off. I still don't know what caused it to kick on. I checked pressures again cold and all 4 tires are even and correct. ¯\_(ツ)_/¯

Oh well. Thanks for the information in this thread :)

See what I asked above about how close you park to the original tires with the original sensors...