According to my disclaimer packed operator's manual, it seems that the US version (TPMS) only indicates low tire pressure, where the Canadian's (Advanced TPMS) shows the actual pressure in all four tires. This is a little bit of a disappointment since I love the TPMS on my Duramax. I find it to be spot-on accurate compared to conventional tire pressure guages.

Is this a software difference or different equipment altogether? It would be great if GL could be re-programmed to show the pressure in all four tires and not just give a warning light when the pressure drops in them. I was of the impression that this is going to be standard equipment on all US cars and trucks in the very near future.

 

There's been discussion about this a few months ago and I if I remember correctly the sensors are in the wheels but the individual pressure function is not active nor can MB dealers alter the software. Many of us are a bit perplexed by this .

 

TPMS meets the standard requirements. I have the individual readings for each wheel on my S and will really miss that feature. I depend on.

As far as knowing if the individual reading can be activated by software update I don't know. I am going to check with my friendly rep. The display capabilities may not be available on the MFD on the dash to allow for it??? Also, the it may require a different sensor on the wheels.

 

My rep said "no"....I hope they change to the more sophisticated version for later model years!

 

I was told no as well..........

 

True, the GL does not have TPMS... it has TPWS.
TPMS has actual radio transmitters in each wheel.
TPWS uses the Anti-lock brake system to sense if one wheel is travelling slower than the other three; which would be caused by lower tire pressure.

I was told that you can tell which system you have by looking at the valve stem caps. If they're plastic, you have TPMS. If they are metal, you have TPWS

 

Thanks for the clarification on the two systems.

BTW, you may be right on the caps. My S had gray plastic before I put on AMG Chrome ones to match the wheels...

 

The GL does have sensors with radio transmitters in each wheel - at least my 2007 GL450 does. I can tell you that the rotational method of measuring tire pressure is not used. I know this because my shop broke one sensor when transferring them to my Brabus wheels. Until the new one was installed, I had a constant dash warning light even though the pressures were fine.

Further proof - I disassembled the broken sensor. It has a circuit board as well as a battery. When the new sensor was installed, the dash light went out.

It is amazing to me that MB cannot utilize the signals the sensors are sending to give us actual pressure readouts rather than simply telling us we have a low tire - and not even which one at that! BTW, a broken sensor will cost you ~$250.

FWIW, both my Bimmers use the ABS rotation method and they both have rubber valve stems. My GL has the metallized plastic stems which are needed with stem mounted sensors. That's a sure way to tell which you have but not fool-proof on all cars. Some cars using sensors have then strapped to the wheel and still use rubber valve stems. Note, I'm talking about the stems and not the caps.

 

True enough. My C3500 Silverado has rubber valve stems and registers the tire pressure in all four tires. It has proven to be very accurate and elimintes the need to manually check tire pressures. The only time the tire pressures are checked is at routine services.

 

For what it's worth, I have two sets of wheels for my Escalde, summer & winter. Both sets have tire pressure monitors that read exact tire pressure to the dash. Both sets have metal valve stems, but this could just be a coincidence.

 

If you have metal valve stems and a pressure monitoring system, you will have stem mounted pressure sensors. The system can report actual pressure, as is the case with your Escalade and Canadian GL's, or a more limited function - as is the case with US GL's.

If you have rubber valve stems and have a pressure detection system, it is most likely using the ABS-Rotational method. The exception is those rare systems that banded the sensor to the interior rim of the wheel.

If you have a metal valve stem and no pressure monitoring system, it's

 

Actually, the newer GM's (2007) have a rubber valve stem, but there is a sensor on the other end of it.

Also, the direct tire pressure system (sensor in the tire) is the only method that currently covers all the requirements that the government has for tire pressure monitoring, so all cars manufactured after 9/1/2007 have the direct system (and most in the past year or 2 as well). The indirect system (using the ABS system), because it detects a difference in pressure between left and right only (so if both left and right are down the same amount, it will not detect a problem), does not meet the government requirements. Audi does have a system in development using the ABS system that will meet all the requirements, but changing from the OE tires can affect it...even a change in rolling resistance from OE will affect it.

Oh, and Ford seems to be the only manufacturer that has gone back to the band type sensors. In this case, the sensor is attached to a band that is wrapped around the wheel.

 

Thanks for the updated info. I didn't know GM/supplier had developed a sensor attached via a rubber stem.

 

Here's one on ebay:

http://cgi.ebay.com/ebaymotors/GM-Fa...em270166110640

From the outside it looks just like a regular valve stem.

 

So that's what they look like. By the way, the dealer sells them for $110, so the $25 on ebay looks good, if you need one.

 

It's $60 installed at discount Tire.