Today while taking a long drive to Boca Raton I saw a weird situation. While going down there I noticed the rear right sensor went to XX on the DIC. After a while, it went back to normal reading 31 or 32 psi and this happened twice. Coming back home, I noticed it happened again. Then after that, the rear left one went to XX and rear right was ok. A few minutes later both of the rears went to XX and this happened twice. I only saw the "Services Monitoring System," or something like that once.

This has me confused as to what the problem could be. I never noticed this before in the past two months that I've had new tires, wheels, and sensors.

Anyone has a clue?

Thanks in advance,
Martin.

 

Hi Martin

Just for anybody else interested in this, Martin called me while he was driving and first experienced this. I asked a couple of questions, but Martin's answer didn't give the clue I was thinking about.

So.....I'm not sure what would cause this. It sounds like an intermittent transmission by the sensors, or intermittent reception by the TPMS.

When the car is still/parked for more than 15 minutes, the sensors go into a "sleep" mode to save the batteries. They only transmit their ID# and pressure data to the TPMS approximately once every hour.

When you start driving and the wheels start turning, the sensors transmit once every 60 seconds (or some sources say 15 seconds).

Once you start driving, the TPMS is expecting the sensors to check in. If you have one bad sensor, or if you put 2 wheels on the back, for instance, that don't have sensors, the TPMS will pick up the operating sensors and know that all 4 should be checking in. In this case you will get an almost immediate message and light that you have a sensor problem if at least one reports and at least one doesn't.

However, if you run with no sensors at all the TPMS is waiting for them to report in, but, according to the Owner's Manual, it will take "approximately 60 minutes" for the TPMS to finally determine that they aren't there or aren't working properly before it gives you a "Service Tire Monitor" message and "XXpsi" on all tires.

That's what I thought might have happened to you, Martin. But I would expect all the sensors would show "XXpsi" shortly after the first one did. But apparently that didn't happen.

I know you put on flared fenders and bigger wheels/tires with new sensors, and that's why when we talked on the phone I asked if you had your old tires nearby in your garage. If your new sensors were never "registered" properly then the TPMS might be picking up the old sensors in the old wheels/tires every time you pulled into your garage. If you never drove for "approximately 60 minutes" without shutting down the engine then you'd never get the DIC message. Every time you shut down and restarted the TPMS reset itself so it would display the old tire pressures of the tires that were stored in your garage.

I don't think that's the case with you either. I think you said that your old tires were not near where you parked the car.

Did you get new sensors in all 4 wheels? If so, the new sensors may never have really been registered properly. If that's the case, then they never have been displaying the pressure in the tires you presently have on the car, even if the old tires are not nearby.

Before this event, have you driven more than one hour straight without shutting down the engine since you put the new tires on in November?

When we talked on the phone I mentioned that the sensor's batteries have a design life of 10 years, so yours shouldn't be anywhere near the point where they're getting weak.

The only other thing I can think of is that the sensor transmission is kind of weak. Did they put the sensors in the valve stem holes, or did they attach them inside with bands? If they banded them, they sometimes cut the valve stem off. The valve stem is part of the antenna, so if it is removed the transmission may not be as strong. You mentioned that you wondered if the sensors had broken off and were loose in the wheel, but I don't think that's a concern, unless maybe they were banded inside the wheel.

So, I think
1. The sensors aren't properly registered.
or
2. The sensors were banded in the wheels and they cut the valve stems off and you have weak transmissions that skip a beat every once in awhile and give you intermittent indications of a problem.

Sorry this was so long, but I was kinda writin' while I was brainstormin'!

If you continue to have problems, come on up and we'll try to do some diagnostic stuff with my tire sensor reset tools.

BTW, I saw some pictures of the show in Boca and it looks like it was great!!!

Bob

 

Bob, thanks again for all your help with my questions. To answer a few of your questions. I don't think I have driven more than an hour after the new sensors were reset. The tire shop did not put bands, instead they put a bracket. As far as I can remember, they did not cut anything off the sensors. They did had problems resetting one of them, the rear left one was a problem. At the end they were able to reset it by lifting the car and pointing the tool right on the middle of the tire. I do know that the sensors were reading the correct psi, because this morning it was reading 27 psi which seem normal since it was cold. I have not been close to my old sensors in a long time, so that is not the case with transmission conflicts.

I will try and see if I can take it back to the tire shop or will arrange something together so we can figure out what could be wrong. Have a nice weekend Bob.

 

Tire bead lube inside pressure port on sensor? When heated getting into mechanism/electronics?

Just an off the wall theory.

More likely, cut off stem related.

-CKB

 

Not really off the wall, Goodyear does not want you to use instant flat fixers because it plugs the sensor inlet up. It is in their run flat literature that came with my Vette. Another thing from the manual, they want you to get up to 15 mph for updated reading from sensor after filling tire with air.

 

To be honest, I don't know what is wrong. But, every time I turn in the car either in the morning or when I go back home. I can read all the of tire sensors with different values. That means that the sensors are sending data to the computer, I just don't drive it more than an hour though.