Re: Anyway to disable the tire pressure monitor system on a 2007 ford escape?

If it's anything like a Ford Taurus I rented, it can produce wacky false positives when the tires get warm on the highway.

Dave

The year of the Taurus would be a factor.... Early TPMSs used ABS wheel speed input for tire pressure computations.... this was NOT a good system.

Later years/models used valve stem mounted transponders... much better but still not "great".

Since TPMS is federally mandated in the US, these systems use a rim mounted sensor... a very good system if the tire shops realize that demounting a tire incorrectly can destroy a sensor.

Judging from the number of low tires we can see on our daily commute to work, TPMS is long overdue.

Ed... Some people will install an alternative wheel/tire combination that may desire lower than manufacturer tire pressures - or, for some unknown reason, decide they want to run their tires at lower than recommended pressures.... On current model Fords, the low limit of the tire pressure tolerance cannot be adjusted in programming. I understand Fords reluctance to allow this since the liability could be astounding.

Every time the manufacturers try to improve convenience and safety, someone, somewhere will complain. These people would have us riding around in cars powered by magneto sparked, flat head, updraft carbbed "flivvers".... but that would only give them other stuff to complain about...

For the original poster... disabling the system is, in the US, against the law.... period. While the system is not yet officially mandated in Canada, any government vehicle inspections I perform include the disclaimer that "if there is a factory installed device...." this includes a catalytic converter (though Alberta has no current anti-tampering laws), any supplemental restraint systems, lighting, seatbelts... the list goes on.... "... they must be functional". What this means... even though we have no federal or provincial mandate currently in place regarding TPMS.... if it is equipped with this feature, it MUST be functional.

Yeah, I hear what your saying. I did have a tire that was low. The TPMS light came on alerting me to this. I filled the tire back up and checked the other ones. The light won't go off now. I just wish they had a easy way to reset it. Thanks!

The light should reset automatically. Did you check the spare? Some vehicles have 5 sensors (my SO's RAV4), some 4 (my Frontier). Both me and the SO have had the lights come on, in my case one of the four rooad wheels was low, for her it was the spare. For both of us, inflating the tires to the proper pressure turned the light out.

Ed

After the tire pressures have been adjusted, the vehicle needs to be driven at at least 30 kph to turn the light out. To conserve the "lifetime" batteries, the transponders go to "sleep" after very short periods of inactivity.

Thanks for the feedback. Will check the spare and drive it a while :)

Follow up. The spare tire was about 10 psi low.Filled to 60lbs. Put

30lbs. in all the way around while the tires were cold. Drove a couple hundred yards down the block and the light went off. thanks again for the help :)

TPMS is a major scam due to a number of reasons. The most obvious is related to pressure fluctuations due to temprerature changes. And not only between seasons but between day and night. If you happen to leave in a state like Colorado, the difference between day and night can easily exceed 50 degrees. This means that if you set pressure to 32 psi for 30F, @ 80 your tires may simply explode. Adjusting pressure for something in the middle, let's say 50, will trigger the light in morning. The second - long term - spam aspect is that today's sensors have built-in batteries which means that they should last about 5 years. If your tire gets stolen, you end up paying $300+ to a friendly crook dealer because the sensor needs to be re-programmed to communicate with the on-board computer. Replacing all 5 sensors will run about $1,500, and this cost is not taken into consideratio when manufacturers evaluate "cost of ownership". Don't tell me it's not technically possible to make sensors that run forever and compensate for temperature fluctuations because IT IS POSSIBLE but in the current form, it is a MAJOR scam. Why do they use system that obviously is not ready for user-frienfly utilization? Simple: each sensor is an active transmitter with its own unique id, and it makes it real easy to monitor your whereabouts. Welcome to the New World Order kgb could've only dreamt of!

And when the tires get hot, and pressure jumps 30-50%... what then?

And when the tires get hot, and pressure jumps 30-50%... what then?

Huh? 30 to 50% - NO WAY. Dry air is close to an ideal gas, so we can use the ideal gas law as a decent approximation of what occurs as the air heats up.

PV=nRT

V, n, and R are constants (Yes V is a constant, the volume of a tire changes very little because of changes in pressure)

so

P1/T1 = P2/T2 and P2=P1*T2/T1

T must be in an absolute scale (Rankine or Kelvin)

70 degrees F = 530 degrees Rankine Assume P1 is 35 psi Assume T2 is 130 degrees F = 590 degrees Rankine

P2 = P1*T2/T1 = 35*590/510 = 40.5 psi

40.5 psi = 16% increase and this is extreme, tires rarely get as hot as 130 degrees F unless you are racing on a hot day. A more normal increase would be 10% or less.

Ed

You are wildly over estimating the change in pressure due to a change in temperature. See my other post in this thread for details.

Assume night time temperature is 30 degrees F. This is 490 degrees Rankine (absolute tempearture scale). Assume daytime high is 80 degrees F. This is 540 degrees Rankine. Assmue the pressure at 30 degrees F is 32 psi. The pressure at 80 degrees F will be:

P2 = 540*32/490 = 35.3 psi . The tires are not going to explode at this pressure.

Ed

If you had that system on whatever you happen to drive, you's be just as annoyed by the ligh constantly coming on as I am. But there is an option - actually I'd prefer that option for myself if it were possible - talk to dealership service people, and ask how many cars come in every day because the TPMS warning light is on.

Honestly, I didn't do the math. My review was based on personal experience of having the darn warning light always blinking because some moron stole my spare tire (with the sensor) AND it comes - and stays - on sometimes a few times a day following temperature fluctuations and changes in travel speed. Trust me it's annoying! But it's even more annoying when some idiot tells me "no, you can't disable the system because it's a safety item, and - therefore - is illegal". Holding me a hostage of their stupid (yet certainly profitable) games - that's what should be illegal.

You left out one thing: the tire pressure when the gage reads 32 psi is actually 47 psi. The gage reads the difference between the pressure in the tire and the atmospheric pressure. The atmospheric pressure is about 15 psi, when the gage reads 32, the pressure is 32 + 15 = 47.

So the pressure at 80 F would be about 36.5, still not enough to blow the tire.

Jeff

As far as the stress on the tire is concerned, it is gauge pressure that matters - unless you are taking it into outer space. It you drive from sea level to Denver, the apparent gauge pressure would increase by 2 psi or so, but I don't think this puts you in any danger.

Ed

Not sure. One of the reason for ford exploder rollovers have been determined as ford's recommendation to keep tire pressure @ 29 psi to offset suspension defects. This drop of about 3 psi - apparently - was enough for tires to explode and contributed to quite a few deaths. I inderstand that 29 is LESS than 32 but temperature in tires with low pressure tends to increase more than in those properly inflated.

Of course, it's not enough to just blow the tire but if you are driving @ 75 mph (legal speed in many states), increased initial pressure will be added to that created by yet another temperature jump caused by friction. Again, remember exploder escapade? But even if you don't get killed, the temperature fluctuations still cause annoying light to come on. For that I don't need calculations to claim.

It is incorrect to say that the suspension of the Explorers from the mid to late 90s was defective. Ford decided on the lower pressure (26 not 29) to reduce steering response so that it would be harder for a driver to get the vehicle sideways when making violent maneuvers. As been pointed out many times before, 26 PSI was well above the minimum pressure needed to adequately support the weight of a fully loaded Explorer. According to the load versus inflation pressure tables for the tires installed on an Explorer from the era that supposedly had a problem, 22 psi was adequate to support a fully loaded Explorer. Firestone never actually claimed that 26 psi was too low, they actually claimed that a higher pressure would provide a greater safety margin. In fact this was total BS. Firestone made crappy ties and when things went bad, they tried to blame Ford and/or Explorer Owners (for not adequately monitoring tire pressure). I am willing to agree that Ford deserves some of the blame for trusting Firestone to build anything better than crap. Just remember these facts:

- In 1996 50% of the Explorer sold had Goodyear Tires, and there was no history of those tires failing at an unusual rate, despite having the same pressure recommendation.

- Other contemporary SUVs had similar size tires with similar pressure recommendation and they did not experience high tire failure rates.

-There is no history of problems with tires on Explorers since the defective Firestones were replaced

- 4 Door Explorers in the range that were supposedly prone to rollover, had the second lowest rollover death rate of any mid sized SUV. Only the Jeep Grand Cherokee was better. 4 door Toyota 4Runners from the mid to late 90s had a rollover death rate 4 times that of 4 door Explorers.

Ed

If "to support weight" means not hitting rims, 22 psi is sufficient. As far as explorer being not defective - suspension- or otherwise - I respectfully disagree. It's always been an unbeleivable piece of junk all around. See, I've been doing automotive inspections for extended warranty companies for about 20 years, and what I've seen in the field... you don't want to know. Just to illustrate my point:

until late 90's, ford had a nasty little defect - among others -the right lower control arm rear bushing had a tendency to deterioratedue to close proximity to the catalytic converter. Apparently, evenford finally realized that it was a problem and started installing ashield. But it was a typical "ford solution", and didn't fix a thinguntil they eventually re-designed the entire suspension. Excessiveplay in that bushing was at least a contributing factor in ford-related fatalities. Now, I'm the last one to say that firestone tires are worth talking about not to mention buying BUT 1. goodyear is unlikely any better and

1. the same tires on other vehicles caused no known accidents or other concerns. The latter fact tells me that whatever was at fault, it wasn't tires.