TPMS light flashes then solid - Dealer suggests new car battery

Originally Posted by Unclemeaty

Wow lots of negative responses to my dealer suspecting the main car battery. I'm not sure what I should do now.

While I was there, the dealer did the full reprogramming of the TPMS sensors but the car only went about 10 minutes before the lights flashed/solid once again. Supposedly the dealership can tell if one of the TPMS sensor batteries is low, or otherwise a defetive sensor. The dealer claimed neither to be the case.

I wish I had a spare battery just sitting around for a proper test... but I did try something. While cruising this evening, I noted carefully the voltage gauge. While first running, its 14.2v. After about 30 minutes the voltage drops to 14v. I tried something, which may not be conclusive of the problem but a possible direction. I loaded the battery down with accessories and stereo while cruising, and the voltage dropped again to about 13.8v, again while cruising. At idle, loading down the voltage is quite easy hence why I did this while cruising. A few minutes later, the TPMS started flashing. I quickly turned off all the accessories I could, shifte to a lower gear to get the alternator spinning faster, and got the voltage back up to 14.0. The TPMS stopped flashing 30 seconds later and remained off until i got home. Interesting to say the least. The dealer said my alternator is 100% perfect.

BTW, my car is an '09 with 48,000 miles on it.

For my next test, I'm going to supply a 1A trickle charge to my battery over-night. Lets see if that helps the problem tomorrow morning.