[Scrounge]

Something similar happened to me on a 2008 Impala. After some cursory research, one of the recommendations was to just disconnect and reconnect the battery. That cleared the error, at least temporarily. I've not driven it since then, hence no updates. Here's the thread:

https://www.allpar.com/forums/threads/inherited-impala.162758/

Don't know if that will work for your Jeep, but you might try it.

 

[valiant67]

The sensor number is determined by which receiver on the car it is communicating with. So sensor #4 is always going to be in the same place even if you rotate the tires. At least that is the implementation in the Chrysler service manuals I've read.

 

[ImperialCrown]

Newer vehicles can determine the position of sensors after a couple of miles or a few minutes of driving (the car has to be in motion for the transmitter/transducer to signal the receiver). Each TPM has its own unique ID signal.
Older vehicles needed the sensor ID # programmed into the WCM (wireless control module) in order to identify it.
There are usually 3 receivers (each in 3 of the wheelwells). It knows by default where the 4th transmitter is if it isn't in the close proximity of a wheelwell receiver.
The WCM is capable of storing fault codes related to TPM issues.

 

[Rick Anderson]

Good Points all.

@Scrounge I may try pulling the battery cable. The codes and diagnosis all point to a bad tire sensor (that uses it own battery) that is stuck at a false pressure, but you never know, by hard rebooting the WCM, that may force it to interact with sensors and maybe that might create a change in the sensor. i.e. it can't hurt to try, but based off what I know, I really doubt it will work.

@valiant67 Yep, it certainly appears to that numbers for the sensors are assigned by positions of the wheels relative to the vehicle. The FSM does say to confirm it, and its smart to do it if you have the ability to read the sensor pressures, by deflating and inflating tires looking for the change. I didn't find the positions described in the FSM, it might be there, I just missed it. But good thing I did confirm positions, cause my logical assumption that the rear wheels would be numbered left to right was wrong, they start at the Front Driver Wheel and move clockwise as they assign numbers, for an XK at least.

On an XK at least, TPMS sensor positions look like this:
#1 #2
<- Driver (Looking from above)
#4 #3

@ImperialCrown Yep, there are many different TPMS systems and many work differently, but one operation I've seen/heard for most is that it requires a few miles of driving for all information to pass between sensor and trigger pt/transmitter/receiver. It makes for the good advice of NOT assuming anything about the TPMS system after a change until you've driven the vehicle a few miles.

 

[Scrounge]

From what I've read, the computer, or at least the part of it that controls the TPMS, might be too sensitive in the Impala. Don't know about your Jeep, but it's the same tire. Most of the Impala's driving was in Michigan, which has notoriously bad roads, so something could have jarred it.

 

[Rick Anderson]

I don't know about the Computer being too sensitive? As far as the computer logic, its simple, "IF pressure is below X pressure, light the light". I think it gets complicated with the radio communications and signal processing of the radio signals. The computer handles that as well, so you have a point that its involved.

I seem to remember a thread about a Ram TPMS problem a Dealer could NOT fix after multiple tries, FCA sent a corporate expert to the Dealership that was able to fix the problem with a software flash. I forget the exact problem, but remembered it was something going wrong with the equipment between the good sensors with tires at good pressure and the light itself, which is pretty much the computer. So technically the computer wasn't "too sensitive" it was the computer was just plain "screwing up, concluding the wrong thing from the inputs it got".

 

[Rick Anderson]

I ordered a new sensor from rockauto.com for about $35, aftermarket Denso, designed as a direct replacement for my particular year/make/model and thus does NOT require programming. There were cheaper alternatives, but I doubted the quality of those and spent a few extra bucks for the Denso. The Airtex appeared to be the exact same thing for cheaper, but ever Airtex part I have purchased failed far too early, I won't touch that brand ever again.

The Denso have a the rubber valve stem instead of the all metal valve stems.

I'm retired military and get to use the auto hobby shop at the local base, that has tire mounting and balancing machines. This tire mount machine has a bar to will force down a tire at the sidewall, so I only had to break the outside bead and compress the tire a bit by the valve stem to have the room to replace it.

This is why they have switched to a rubber covered valve stem, the OEM stem was totally seized up, nut rounded off, I finally had to carefully use a high speed cutting wheel to remove the stem, by breaking the old OEM sensor off the valve stem and cutting off the back side of the stem, where there is room to cut without damaging the wheel.

The Denso valve stem is a solid brass core, I think it has to be to act as the antenna for the sensor to communicate. BUT, its not just a thin rubber coating, its a thick rubber valve stem with the brass tube embedded deep inside it, the base of rubber stem is a lot of rubber and it has give and flex like a regular rubber valve stem. Hard to describe, but although the stem itself is rigid, the thick rubber base allows it to have give and take. It mounts just like a regular rubber valve stem, it just has a sensor attached to inside end of it.

The Denso sensor is smaller and lighter, and sure enough, I had to remove weight to balance the tire.

All done, and start up to leave and the TPMS light and warning come up still, despite the brand new sensor that does NOT require programming. I don't panic, I remember IC's and I discussion and cross my fingers that it will register the new sensor after a few miles of driving. Sure enough, 1.3 miles down the road, the TPMS light and warning go out and stay out.

I think this is because of the radio communications. Since the sensor is linked by radio to the system, its possible if you're parked next to a car with the same type of sensors, for the system to pick up the other cars sensors and register the wrong sensor. So, to prevent that, the system waits until you've driven a mile or more with only detecting that one sensor before it registers it.

Theoretically, if you drove side by side the whole time with another vehicle with the same sensors, it could resister the wrong sensor or at least NOT register the sensor until it only picks up one sensor for more than a mile of driving.

 

[NYBo]

I believe the sensors go into sleep mode after the wheels stop turning for a certain length of time to extend battery life.

 

[Rick Anderson]

That may be true and I can see that, but I think at least part of the "you have to drive a couple of miles" is the logic they program the TPMS computer, so that it doesn't accidentally register sensors from a vehicle parked next to it. I remember reading that somewhere and it makes sense, as well as the sleep mode when the wheels aren't turning.

 

[Rick Anderson]

Update;

I just put on a fresh set of tires and decided to do the remaining three OEM TPMS with new aftermarket TPMS sensors, knock them out while changing the tires. RockAuto had Schrader TPMS sensors on sale that are pre-programmed for my make and model, they appear identical to the Denso (when I got them even the packaging is identical). They were only $20 a piece and they work great. Rubber stem just like the photo of the Denso above, in fact the Schrader is identical to the Denso. I suspect the same manufacturer, just different distributor/brand.

A couple of points:

In another thread someone posted they didn't get new pre-programmed sensors to register for hundreds of miles when replacing all the sensors at once. I worried this would happen. It didn't, one new sensor register within 1.3 miles of driving for me. 3 new sensors registered within 2.1 miles of driving for me.

Getting the old OEM metal bolt on stems and sensors out of the wheels. Despite using a service kit to replace this hardware last time I changed the tires, within 66k miles, every bolt together valve stem corroded so badly it could NOT be disassembled as intended. I even sprayed them down with penetrating oil everyday for week before attempting to disassemble them, they were still seized solid and were a major pain to get them out. Well except the one that the nut crumbled into several pieces, that one came out easily. So, get the rubber valve stem versions when you replace them and avoid this pain when they corrode and seize up.

Best way to get the old OEM metal stems out when they are hopelessly seized up. Chisel/Hammer/Bolt Cutters. Use the chisel and hammer to split the plastic/resin sensor body where it attaches to the valve stem, the plastic/resin sensor will come off the valve stem giving you room to work on the valve stem. Why bother with the time and risk of damaging the wheel cutting/grinding off the end of the valve stem, or gripping it with vice grips, the nut will just round off anyway, I took bolt cutters to the end of the valve stem, cut it off in a few seconds and it comes right out. Of course chiseling off the plastic/resin sensor body destroys the sensor, circuit board split right in half.

The newer TPMS sensors (mine were 2010) are coming OEM with rubber stems or at least with screw attached sensor to stem, so removing the stem from the body shouldn't be as difficult, its the earlier sensors 2010 and earlier that have these problems and may require destroying the sensor just to get the valve stem out.

Mounting the valve stem and sensor after getting the tire on the rim. There is always the possibility you can damage the sensor while mounting the tire and pulling the bead over the rim. I'm sure this will depend on the size of the tire and rim. My Jeep has 245mm wide tires on a 17" wheel. I had the room with this size tire, that I could get the entire tire over the rim, and push the sidewall down and insert and mount the TPMS sensor after the tire was on the rim, thus avoiding accidentally damaging it while pulling the tire bead over the rim. Then I inflated the tire to seat the bead on the rims.

 

[MPE426HEMI]

The metal aluminum stems are known to corrode apart and the plastic one's, like a relative of mine found out the hard way, weaken over time and snap off while trying to refill with air, leaving you stranded with a complete flat. Rubber is the way to go.

 

[Rick Anderson]

The metal aluminum stems are known to corrode apart and the plastic one's, like a relative of mine found out the hard way, weaken over time and snap off while trying to refill with air, leaving you stranded with a complete flat. Rubber is the way to go.

And just as bad, when you go to replace the old aluminum stems, you can't get them out because the hardware has corroded together so badly.

Depends on the design of the TPMS sensor and stem, it looks like all the newer ones have learned this lesson, and there is room to cut the stem and sensor apart without damaging the sensor, NOT to mention avoid it altogether by using rubber valve stems.

The earlier TPMS sensors had the metal stem go through plastic body of the sensor, with a thick metal spacer/washer, and a thin collar nut on the outside. No room to get in there to cut out a seized stem, the thin collar nut on the outer portion of the wheel is so thin it rounds off right away. The only way to really to get a badly corroded stem out, is to use a chisel to split the plastic body of the sensor open and break it away from the stem, then you have room to cut off the end of the stem and get it out.

Of course most folks on this forum don't have access to tire changing/balancing machines like I do. They have to take the vehicle to a tire shop and let them deal with the old TPMS sensor seized into the wheel, which the shop probably learned these lessons long ago about the early TPMS sensors and how to get the seized up hardware off the wheel quickly and easily.

 

[Rick Anderson]

Oh, the first time I changed the tires on my XK at 80k miles, I replaced the stem hardware with the service kits, the vehicle was newer and only been through several mild winters. So the hardware came apart, although it was tough. This time, we have had more severe winters in my area the last couple of years, more road salt, etc, I'm sure that is why the stem hardware was much more seized up then the last time I did it.

 

[Stratuscaster]

I just had the tires replaced on my '06 T&C at the local Discount Tire. Two of the TPMS sensors were already replaced - one rubber, one metal - and during the tire change they were able to rebuild one of the remaining metal ones and I needed to replace the other. It's been at least 2 weeks since and the TPMS light is still on.

I have to agree - when they go, replace them with the rubber stem versions.

 

[MPE426HEMI]

And just as bad, when you go to replace the old aluminum stems, you can't get them out because the hardware has corroded together so badly.

Depends on the design of the TPMS sensor and stem, it looks like all the newer ones have learned this lesson, and there is room to cut the stem and sensor apart without damaging the sensor, NOT to mention avoid it altogether by using rubber valve stems.

The earlier TPMS sensors had the metal stem go through plastic body of the sensor, with a thick metal spacer/washer, and a thin collar nut on the outside. No room to get in there to cut out a seized stem, the thin collar nut on the outer portion of the wheel is so thin it rounds off right away. The only way to really to get a badly corroded stem out, is to use a chisel to split the plastic body of the sensor open and break it away from the stem, then you have room to cut off the end of the stem and get it out.

Of course most folks on this forum don't have access to tire changing/balancing machines like I do. They have to take the vehicle to a tire shop and let them deal with the old TPMS sensor seized into the wheel, which the shop probably learned these lessons long ago about the early TPMS sensors and how to get the seized up hardware off the wheel quickly and easily.

Yes you're correct, you can't get them apart because the aluminum one's have those retaining nuts on the outside, where of course all the elements are acting on them all the time. Just total garbage! Makes me wonder sometimes if people who design this stuff actually understand it? In my opinion, if your an off roader, the last thing you want are solid stems. If a rock happens to swipe a rubber stem, at least it can get out of the way. The plastic and metal one's and it's Oh Sh#t! Oh Sh#t!!!

 

[MPE426HEMI]

Oh, the first time I changed the tires on my XK at 80k miles, I replaced the stem hardware with the service kits, the vehicle was newer and only been through several mild winters. So the hardware came apart, although it was tough. This time, we have had more severe winters in my area the last couple of years, more road salt, etc, I'm sure that is why the stem hardware was much more seized up then the last time I did it.

Just for info's sake, is there anyway to replace the battery in these Rick? I remeber the older type had resin or shellac in the backside which people carved it out with a dremel tool and refilled it with epoxy afterwards.

 

[Rick Anderson]

I have seen photos on the internet of people hacking them to replace the batteries inside them.

I'm guessing, since they have to be reliable and rugged and withstand lots of shock and g-forces, an opening compartment to replace the battery would just compromise that, so they mount the battery permentantly to make it more full proof during the life.

Besides, I have yet to have the battery go dead on a TPMS, the one that failed on me was sensor failure, battery still going strong. I replaced the other three cause I am coming up on the end of the battery life before I'll need a new set of tires, so I did it early to avoid having to dismount, remount and re-balance tires when the battery eventually goes dead.

6-8 years I've been told is the life of the battery.

And yea, I agree, a rigid valve stem off road? Talk about just asking to have the valve stem snapped off and leaving you stranded.

 

[pt006]

I have learned a lot from the above discussion. Thanks.