Question On Tire Pressure Monitoring:

I Was On The Interstate (I-77 - Charlotte), Tire Pressure Warning Light Illuminated. Oh No, Not Again!
Pulled Onto Shoulder, Did Visual Of Tires, Nothing Appeared Low.
As It Was Only 5 Miles To Dealer, I Drove There.
As I Waited For Service Tech To Check It Out, I Used My Tire Pressure Gauge To Check The Tires. The Front Tires Both Had 30 Psi, The Passenger Rear Had 27 Psi, The Driver Rear Had 40 Psi.
The Passenger's Rear Had A Flat (Roofing Nail) Only A Week Prior, And Since It Was The Lowest Reading (27 Psi) I Told The Service Tech That I Suspect This Tire Was Triggering The Sensor.
The Driver's Rear Had A (Screw) Flat About 4 Weeks Prior And I Never Checked The Psi After The Repair.
Well, The Service Tech Took The Car Into The Service Bays And Returned 20 Minutes Later And Informed Me That The High Pressure Tire (Driver's Rear - 40 Psi) Was Causing The Sensor Alert. I Told Him That The Tire Was Repaired 4 Weeks Ago And It Seemed Strange That I Was Just Now Getting The Alarm. The Tech Said To Drive The Car And If The Warning Light Came On He "would Check It Out Further".

I Took The Car Home And Used It This Weekend With No Problem.

I Checked The Service Manual And Owners Manual For The Tire Monitoring Sensor And There Is No Mention Of An Over-inflated Tire Causing The Sensor To Send An Alarm.

Has Anyone Got An Insight Into What May Have Happened And If The Diagnosis Is Correct. I, As I Sure Most Of You Too, Do Not Like Driving Without A "spare" And Running The Risk Of Shredding The Tire And Destroying The Rim.

 

The 27 psi in the passenger rear tire should definitely trigger the light. You have 3 tires under inflated but the passenger rear was the problem (most likely). While over-inflation isn't good either, I don't think it caused the monitor light.

 

I looked through the repair manual and it does not reference "over inflation" triggering the TPM, nor would I think it would. 40psi is not "over inflated", most OEM tires are recommended to 50-55 psi hot running temp.

I would guess your 27 psi did the deed, especially if your reading was 27 on a hot tire. That would mean your cold psi was somewhere in the 22-24 range... Most tires will increase psi by 10% from cold to hot.

 

Another example of a Five finger dealer not knowing sh*t about this car. The reason the Crossfire will be discontinued is because of two reasons.

1st Can't fix to save their as*
2nd Don't know how to sell this car.

You don't discount your best product.

OK I am done. Sorry.

 

I keep all of mine at 45 psi, I like to feel the road at least a little bit. And I don't believe that the pressure sensors will trigger when pressure is too "high".

 

Swellclub, what the heck are you doing? Rallying through old construction sites? Seriously, the TPS does not trigger on High tire pressure. It will only illuminate the light if a tire is about 25% below pressure of if the battery in a sensor has gone bad.

 

According to the Factory Service Manual, the TPM is triggered at 26 psi or below...however, there is a note regarding changes (be they higher or lower?) of more than 1 psi between revolutions will also trigger a TPM error....hmmmmmm...might be that a sudden change of differential between readings could cause the light to be triggered, it is got both an absolute (nnn indicates low pressure AKA 26 psi) and a relative (differential between last reading and current) threshold for trigger...just a guess...ct

 

All I can say is you must have botox injections in you backside. I haven't (and won't) try running at 45 psi but I would imagine the car is skittish on rough surfaces and lacks traction, in time I would guess the middle of you tires will wear out long before the sides.

 

Bobs is right...the TPMS will not come on when you have a over inflated tire. With that said the TPMS will come on when there is a 25% (8 lbs) pressure loss. Now if there a is combination of tires that equal 25% ( say...all tires are each 2 lbs low) the TPMS will trigger.

 

Holy sh*t!!! Traction has to be horrible since you probably only have half of the normal 'footprint' that the properly inflated tires would provide. I can't imagine you are feeling much of the road since you are probably bouncing over most of it. But each to his own.

 

Just to clarify... TPMS will only light up if a total of 8 lbs loss - I assume that the 8 lbs loss is calculated from 4 tires @ 26 lbs. If 1 or more tires are over inflated (27 lb or more) that would not effect the TPMS.

 

No...could be any combination of loss pressure per tire. Example; 1 tire with a 2 lb. loss another with a 1 lb. loss another with a 3 lb. loss and the last tire with a 2 lb. loss, the total will equal 8 lbs. and the TPMS will trigger. Now on the other hand if you have 3 or all 4 tires that are low and do not equal 8 lbs. or 25% loss the TPMS WILL NOT trigger. That is why it is important to check tire pressure weekly or bi-weekly.

 

I understand yet is the benchmark for the 25% - 26 lb?
In addition, as I understand , any tire with more than 26 lbs would not affect the 25%.

 

Now I'm totally confused...

Am I wrong in thinking that most of you all own Michelin Pilot Sport tires? And am I wrong in thinking that the recommended pressure as suggested by the label inside the driver's door is 32 psi on the fronts and 33 psi on the rears?

 

I don't understand it either...

It is no wonder that they are having so many problems with the system. If the recommended pressure is used, and it that pressure is checked often, things work as designed (for the most part).

 

No way, Jose'. Here's how it works, quoted from the manual:

Note: The "low" pressure threshold is defined as 26 psi. I couldn't find a reference for "critical" pressure.

DESCRIPTION
This vehicle has a tire pressure monitoring (TPM) system. It is there to alert the driver when air pressure in any of the vehicle’s four tires falls below a predetermined threshold. It alerts the driver with a lamp in the instrument cluster.

The tire pressure monitoring system utilizes transmitters that are located in the valve stem of each tire to communicate the tire pressure condition to the module. If a tire has low air pressure, an indicator light on the instrument cluster is illuminated. The vehicle operator must check the tire pressure of each tire in order to determine which tire has a low pressure condition.


The garage door opener/tire pressure monitoring (TPM) module has a microprocessor controller that can monitor the transmissions from the sensor/transmitters anytime the ignition is on. It can store the last 32 transmissions. There are two important values included in these transmissions. They are:

² Why the transmission was sent,
² Low Tire Pressure

The module compares the transmitted tire pressure from the sensor to the two pressure thresholds (low pressure or critical pressure). If the module determines that the tire pressure transmitted is below the low or critical pressure thresholds, it will signal for the “Low Tire” pressure warning lamp to come on.

 

Ok, are we getting distention amongst the ranks? Will the real definitive TPMS for dummies please stand up.
How does the system work? What is low tire pressure defined as...
25% of the total 4 tires or is it each tire individually.
why would there be a low and critical pressure sensor? Isn't one enough?
Is 26 lb the magic number for the predetermined threshold?

So many questions - is it just me?

 

Too bad it's not like the Corvette's pressure monitors. It tells you digitally on the dash info exactly how much psi is in each separate tire, so you can see which one may be low and by how much.

 

No distention just a little confusion and no help from the service techs. This is the method and formula that I find works for me. I have been told many things from the techs regarding the TPMS, and have not yet got an answer as to how exactly does the system works. I once got a nail in my tire, and the TPMS light came on I checked the pressure, down 7 lbs. Refilled the tire with the proper pressure and went home. The light is on the following morning, rechecked pressure....down 9 lbs., now I know I have a nail/screw in the tire...the left rear tire had a nail in it. Which means the TPMS worked inside of the 25% range for 1 tire, because the other 3 had the proper air pressure. Scenario 2...my Roadster Limited sat up for about 3 months, I went to start the car and the TPMS light came on. All the tires were low totaling 10 lbs., the TMPS would not reset until all the tires were at the correct pressure. So I concluded it is a single sensor that has a threshold of 25%, given the climate zone you live in and will trigger whether 1 tire or all tires exceed that threshold. There have been times during my weekly ritual of tire checking, that there may be a 1 -2 lbs. pressure loss and the TPMS does not trigger.

Hope this makes sense.

 

While we're on the topic, can the owner reset the monitor? Pull a fuse? I did shred a tire the other night, and decided I'd rather take the wheel to a dealer than get towed. After a so-so experience with the dealer, I've got a new tire with a new valve, and a light that won't go out. I gather this is likely because the "serial number" of the new sensor isn't known by my car. I've driven about 2 hours and the light's still on. Can I reset it?