Fix a Flat

Correct.

Actually, the system monitors hub RPM. The hub has what looks like gear teeth on the outer circumference, and the speed sensor is basically a metal detector. As the hub rotates, the teeth pass by the speed sensor and the sensor sends an "on" signal when it detects a tooth and no signal when the gap between the teeth passes by the sensor. The faster the hub rotates, the greater the on-off frequency, and with a known wheel and tire diameter, the frequency can be converted to wheel speed.

Fascinating - Is any of this visible to the eye? Is there a name for this type of system as compared to "the other" kind of systems? Then this should also eliminate any problems with a careless tire change and tools.

The teeth on the hub should be. Look for wires on the strut, follow them down until you find the speed sensor. Look at what the speed sensor is pointing at and you should see the teeth on the hub. BTW, that speed sensor is the speed sensor for the anti lock brake system, and the low tire system just monitors the signals from the ABS sensors.

This is known as an "indirect" tire pressure monitoring system because it infers low tire pressure by noting a different wheel speed for one wheel compared to the wheel speed for the other 3 wheels and is not actually measuring tire pressure. The advantage to an indirect system is that there is no extra hardware in the wheels. The disadvantage is that it is not as accurate as a direct system.

A "direct" tire pressure monitoring system actually measures tire pressure and sends a signal to a receiver in the car. It uses a transmitter about the size of one of those keyless entry key fob. The advantage of this system is that it is accurate. The disadvantage is that replacing the battery in one of those transmitters requires dismounting the tire.

In front I see - using a mirror and light and on my back - a wire or hose at the top and one near the center and the CV boot - no moving parts of the wheel can be seen near the hub. At the rear - see the brake tube at the top and 'a sensor' of some kind near the center of the wheel - whatever it is pointing at is behind metal. Perhaps some disassembly would be required .

There is NO warning in the manual (that I found) about using monkey s*** to fix flats. j

I'm trying to remember exactly where the teeth/splines for the speed sensor are. If the outboard end of the axle has any visible teeth or splines, then that is what you're looking for.

That is probably it.

The absence of a warning or prohibition is not the same thing as approval or endorsement.

We all have our own level of decency. One would think if something common was a known problem then it would make it into a T manual.

Called "THE" Serv. Mgr at the dealership where I got the thing. At the time I was introduced to him and asked him a couple of test questions - which he failed miserably IMHO. This time he again failed to live up to my lowest expectation which was that he would have to call me back with correct info. I asked him about the pressure sensors. He immediately started shooting of his mouth about them being mounted on the side of the rim inside the tire. I reminded him the way it was written up in the manual - and per a very knowledgeable friend on the Internet who may not be 100% up to date - our guess was that it was an indirect system and anything injected into the tire would not affect any sensor hardware. He had me on hold for 10 min while he went and checked. When he came back he was less that coherent - but confirmed that it definitely was an indirect system and that the monkey S*** should not hurt the pressure sensor performance - however the temperature is also picked up and due to the substance injected - a particular tire could heat differently and thus cause a problem. Ray, what do you think about the temperature thing?

In my book a good a good answer by him would be - hold on while I double check to make sure I give you the correct info - and the 2-3 min later give out the correct info. Even if he had to call me back that would be far better than pretending to know and then shoot off his mouth. Makes one wonder why he is the serv. mgr - guess because he either had a green card or spoke English. I don't think I'm overly harsh and can't think of a reason to go back to that place again. The problem is that it is NO different than any other dealership or large shop I have visited over many years.

True, but the use of Fix-A-Flat and Slime is not mainstream, and the folks who write the manuals can't think of everything a consumer might try out.

LOL! You're trusting advice you get on the internet?

He had me on hold for 10 min while he went and checked.

The temperature thing is possible nut IMO, not very likely. It is possible that the slime or whatever may be distributed unevenly and can cause the wheel and tire to be out of balance. That stuff also makes a huge mess for whoever breaks down the wheel and tire to properly repair a flat or to install new tires. There is a chance that the place may want to charge you extra money to clean it up so that the bead will seat properly.

I would not use that stuff as a preventative measure because I don't think it will work. Most sealants, glues, and caulks cure by being exposed to air, which the tire is full of. If you put the stuff in a good tire and it cures (solidifies), then a fresh puncture would not be sealed. If the stuff does not cure and remains in a liquid or semi-liquid state, then it will throw the tire out of balance.

Sensors aside, service professionals and I are not fans of Fix-a-flat or slime products, although I'll admit that I used to carry a can in case I got

From my experience calling on dealership service departments, I would much prefer a service manager that can manage the department over one who is current on technical features but lacking in management ability. I do agree that the manager should have asked one of his technicians rather than guess and come up with the incorrect answer. Service advisors tend to be more current technically than service managers, and technicians are the most current. You are better off asking a technician or service advisor a technical question than a service manager.

It is an art and a science to get correct info anywhere. The web is as good a place as any. BS is generally easy to spot - even when you don't know the answers. Do you not agree?

I believe the stuff I have used generally turned into a fine powder. Then again I never rushed to a tire shop right after shooting up .

How would one locate and then get the knowledgeable technician on the phone?

This turkey is a classic BS artist - he would do very poorly before a judge in court. I once spent a few days looking up everything about detecting lies and who was best or worst etc. This was part of my preparation to appear before an administrative judge. I literally blew the opposition away. In his written ruling the judge stated that ..."had credibly testified that ... When I later called the office I somehow got connected to a different judge who stated ... judge XXX must have been very impressed by the quality of your testimony ..

Then again someone far smarter than me said that on the Net everyone can be whoever and whatever they want to be. To win an argument on the Net is like winning an argument with a small child - you lose. j