Just had an epiphany. One of my TPMS's is original, (16 years old), it may be outputting a strong enough signal that my scanner can read, only being inches away, but the battery is not strong enough to send a good signal to the BCM.

EDIT: OK, scrap that theory. The TPMS was obviously transmitting a strong enough signal to reach the BCM and honk the horn during the relearn attempts.

 

Yes indeed the bcm is getting the signal. Last time I replaced my tires, after relearn the low tire light was still on until I drove about a mile, and never returned since.

 

You will need to drive the car for a bit with the tires at the correct tire pressure to get the light to go out, or if you seriously over inflate them when stationary (40+ psi) I've seen that turn the light off. Don't forget to lower the pressure to spec if you go that route.

If BCM can't read any sensor you would get a SERV TPM message in the dash. The low tire pressure indication is either real, or a sensor that is reading incorrectly.

 

Untrue!

 

Light's out! Drove around for a couple of miles after doing the TPSM relearn and no more light. Apparently one or more of the sensors lost connection with the BCM and the relearn reconnected. The part I hadn't realized was the need to put some miles on after a relearn.

 

And some air in, like 38PSI cold.

 

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Where are you getting 30psi as recommended? You're running 305s; 30 is way too low. The TPMS on our trucks want to see at least 35-38psi.

 

Actually, it IS true. SERV TPM appears if the system isn't working correctly, LOW TIRE appears if one or more of the tires are low. Owner's manual pg 3-45, 3-46, & 5-66

 

Remove antenna at the BCM, take a drive, and you will not see SERV TPM!

 

29psi triggers LOW TIRE!