Low tire pressure system failure!

[leadfart]

I had an interesting anomaly yesterday. I took the beast on a 700 mile round trip excursion to my old stomping grounds. I was on the toll way, less than an hour from home, when the gremlins struck. I was running 90, and all of a sudden, bells and whistles, like when I had my blowout, at 140.

I had a low tire pressure system failure. At first, I thought it might be a blowout or low tire pressure issue, but the tires were rock solid at 90. The DIC showed no tire pressures and a system failure notice.

I got home, tried to clear it, still brought up the DIC notice.

This am put the HPtuners on it, no DTC's, and the system failure was gone. Who knows!!

[Navy Lifer]

Well, I haven't had that happen, but I will add that I'm less than a "fan" of the government-mandated TPMS--it's Nanny Crap.

I had much more confidence in the system used on the 2004 Impala SS that was traded for this car--no in-wheel sensors, but by measuring & comparing ABS signals from all 4 wheels, an alarm would set for a low tire as it's shrinking radius would cause that position to spin faster than the other positions.

I don't know what the differential had to be to turn on the alarm, but at least it was reliable, even if I had to figure out which tire was low. That's what eyeballs & tire gauges are for....but no, that wasn't good enough for the NHTSA nerds.

[The Tech]

I had this pop up two weeks ago. I was driving and the Low Pressure Warning came on. when I scrolled on the steering wheel instead of tire pressures I had a "System Failure" Error and no readings. I pulled over and shut the car off, waiting a couple of minutes but the error came back when I started the car. Like above all tires looked good so I drove the car home. The next morning I was prepared to take it to the dealer but when I started the car everything was normal.

Two days later I start the car to come home from work and the Low Pressure Warning comes on again, this time the LF reads 14 PSI. I shut the car off and get out - the tire appears fine. I know, radials can look that way with low air. So I restart the the car and this time no warning, all tires read 35 - 37 PSI. No repeats since then.

[storm9c1]

These modules use RF signals. It's possible that something temporarily interferes with the signals. Gosh, I could see a trucker with an illegal 1000W linear amplifier on his CB jamming stuff like that all day long. Not to mention the fact that there are many sources of RF near the frequencies that those sensors use. I never did like the sensors or the system. I like the concept of TPMS, but the implementation of putting battery powered RF electronics into a spinning wheel at high speeds, hitting bumps, dealing with constant vibration and G-force, and major temperature and moisture extremes is massively abusive and failure prone. I'm surprised these systems hold up at all.

[Navy Lifer]

I can see TPMS's added value for commercial vehicles - large multi-wheel trucks, buses (both commercial and those used by schools), etc. It makes much less sense to be in EVERY vehicle produced, although it is good for someone who just happened to buy stock in the company or companies that are the main suppliers of TPMS components (ahead of the announcement of the regulation imposition). Gee--what a concept, when you think about how many other tech-based "mandated" things have been pushed onto the public over the years, and who was able to get in line to profit from that new requirement!!!

I object to TPMS from the standpoint of unnecessary cost & complexity. Technology like this, while possible, often suffers at the hands of clumsy and inexperienced tire shop folks. In many places, rotating tires now has added expense for re-setting the TPMS so the position that is in alarm status will display correctly. Unintended consequences (by "gubmint") or the free market doing what it does best?

As vehicles equipped with TPMS age, and get into the hands of 3rd & 4th owners, with less ability to afford, and perhaps even understand, the concept of TPMS (and possibly with no owners manual specific to the vehicle to explain it--if they bother to read the book), it will become a meaningless add-on that is ignored or that someone will get soaked by an unscrupulous "repair" shop trying to correct it out of an irrational fear that there is an impending tire failure.

I suppose there's possibly a fuse that disables the function, but it probably kills the entire DIC display, too, so it either needs to work correctly, or in the end it means driving vehicles (not just PPV's) with the low pressure warning constantly illuminated--a big fat FAIL based on somebody's bright idea and "good" intentions...thanks again, Joan Claybrook!

There....I've told you how I REALLY feel!

[SBRMD]

Amen Bill, your assessment is spot-on. An almost completely unnecessary, distracting and costly exercise. What the hell ever happened to eyeballing your tires when you drive the car, as many of us were taught? My wife and I have a Sequoia w/ TPMS, one of which was horsed up by Midas when repairing a leaker; when I subsequently had the car in to Toyota for a tire deal, they replaced all the rubber and scrambled the positions of the wheels before I could make sure otherwise, then estimated (vaguely) that it would cost me $300+ to find and repair the one bad one, so the vehicle has had it's light on now for 40K miles. FAIL!

[Navy Lifer]

And, I forgot to mention that the TPMS pressure readouts for each wheel position are largely inaccurate, on the order of several PSI. Dealer service says "that's normal".....really???

My local dealer, while good, is no real help to actually correct or improve the system, but at least they're very accommodating as far as re-setting it at no expense--me thinks they recognize what a poor system TPMS actually is, and have decided that they should not pass on the cost of dealing with nuisance indications (assuming inflation levels are correct) that seem to be an inherent problem.

Maybe the system will improve in newer generations of vehicles, but I stand by my original position--it's STILL Nanny Crap.

[SBRMD]

So, do you think that thepressure one gets from a standard tire gauge are more accurate than what comes up on the DIC?

[Navy Lifer]

Probably--assuming the gauge is a "quality" item (good luck with that!) - I have 2 different types that I recently used to check pressures, and found both to read within 1 PSI, so I'm fairly confident that they are "accurate enough", especially compared to TPMS readouts.

One is a Schrader/Michelin "Vigil" - made in France - and the other is a Parker "Tru-Flate" - made in the USA. So, yes, I'm comfortable with the accuracy of these instruments.

I've had both for a number of years--no idea if they may still be available, or made in the same country(s) if they are available. Below are links to each - the Vigil has a range of 10-60 PSI, and the Tru-Flate gauge also has a narrower measurement range (10-50 PSI) which means greater accuracy (fewer graduations on the scale is more accurate in this case) for the default "car" tire pressures we use, than other gauges you might run across or find others using.

http://www.worthpoint.com/worthopedia/v ... -170091923" onclick="window.open(this.href);return false;

http://www.amazon.com/dp/B000NCQXEC/ref ... B000NCQXEC" onclick="window.open(this.href);return false;

Not sure if the Tru-Flate brand is still affiliated with Parker, or if it's (still) made in USA or NA. A quick look at their website seems to suggest that it is no longer a Parker product--as I said, the tools I have are "old".

Technology-wise, digital gauge systems are probably the way to go in the future, as long as you are confident that the readings are accurate.

Yes--it is interesting to compare pressures between being manually-checked and what TPMS says is in each tire!

[Tom Slick]

Actually, the TPMS is quite important on our vehicles... Stabilitrak uses the TPMS data (only when tires are below the "limit") to calculate when to interfere...

Later,
Tom Slick