TPMS Problem

[jakenbake]

So I have an '09 with 70,000 miles and over the past couple months the TPMS light will come on when I am driving. So far it has always happened on the freeway...The light blinks for 10 seconds or so and then stays solid. After about a minute or two more, the light turns off and everything goes back to normal. Over the past couple months this has happened a total of 4 times. I took it to the tire shop and the first time they said all the sensors checked out and reset the system. It then happened a couple more times, I took it back and they tested everything again and once more said that it was fine. The guy did say that the batteries either test as good or bad and that what might be happening is that the batteries keep going out but then get a little boost.

So can anyone verify what happens when the batteries are dying in the sensors? Or what else this might be? I don't want to just start replacing things and wasting money.

[NJGuy]

I had an issue with my tpms that struck my 2008 two times. My light had started blinking when the days got colder. I keep the EX in my garage overnight. After driving for 10 minutes, the light would blink for a minute or two and then stay lit. The light would be off whenenever I restarted the car. I wasn't so sure that it was a bad sensor battery, but it was the culprit both times.

Check the file WT of the FSM. I think that 2009 might be the last year they had the TPMS check switch under the dash by the steering wheel and OBD port. I believe you can enter the TPMS diagnostic mode by grounding the check switch connector. I didn't have any luck getting mine into diagnostic mode, but since you're more skilled than I am you would probably have a much better chance.

In diagnostic mode, I believe you can narrow down where the fault is in the system. The light blinking pattern corresponds with a specifc fault, which are all listed in that PDF file. You may also be able to figure out the pattern when the light comes on during a drive; but in my case the pattern I saw during my drives was misleading.

I wouldn't be surprised if the batteries are starting to go bad, but are getting a bit of a jolt like you mentioned. Like I said, two of my sensors ended up with dying batteries. I can't recall exactly when, but I think it was 2 to 2 1/2 years ago and around 80k. Plus, don't some electronic systems start to go wonky when they get reduced voltage?

If you do end up trying to troubleshoot on your own, please let us know if you find anything out.

[jakenbake]

I did the diagnostic mode and it worked (I think). I grounded the wire and the light flashed a code. According to the service manual, it was code 23 which means that the rear right hand sensor is not communicating with the TPMS system. There is one thing I am not sure of...The diagram in the service manual makes it seem as though the light should flash in this manner..."start signal, then cylce through trouble codes, then once the codes are done it should give the start signal again and repeat". However, I got the start signal and then it just repeated the signal for code 23 over and over for about 20 minutes. I am not sure if the system just stored every single instance of code 23 or if code 23 was the only code. Either way, I gave up after 20 minutes and I will just assume that the sensors all should be replaced now that they are about 7 years old. $260 bucks to get all four replaced. :-/