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Originally Posted by GotSandH3
I know that TPM has been around for a few years now and do know that there are two different versions for it. Im not sure about GM and Im sure your right Fstop, but on a mercedes-benz you can version code the instrument cluster into thinking it doesnt have TPM. Its not turning off the TPM system, but you will get rid of the message in the cluster.
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They have been around for many years. I believe the Vettes got it for the first time in 1997 due to the release of the run-flat tires. Cadillac has had it for many years, and originally, there were at least three different systems.
One system such as used on Vettes/Cadillacs for example, had sensors that were programmed to each corner of the vehicle (LF, RF, RR, LR), so that if tire did start to lose air, the DIC could signal the driver which wheel was low.
The system on the H3 is not corner specific. It monitors four TP sensors, and if one tire goes low, it signals the driver that a tire is low, but does not say which tire.
Then there was the infamous system based upon wheel speed rotation from information obtained from ABS wheel speed sensors. This type of system does not meet Federal Regulations, and had many faults. It used an algorithm that compared all four wheel speed sensors to determine that one tire was rotating at a different speed than the other three. It sometimes took up to a 50 percent lose in tire pressure to signal the system, but the biggest fault was if all the tires were 50 percent low, then the system did not pick up on that since all the tires were rotating at the same speed.
However, any system installed now, it not installed for customer convenience, they are installed due to the Transportation Recall Enhancement, Accountability and Documentation (TREAD) Act. These new systems have to meet National Highway Traffic Safety Administration's, 49 CFR Parts 571 and 585 regulation. The auto manufacturers must equip 20 percent of their vehicles with a TPM system by 9/1/05, 70 percent by 9/1/06 and 100 percent by 9/1/07.
Since it is a Federal regulation, the auto manufacturer will not make it possible for you to shut them off; if they did, they could be found liable by the Feds for voiding the Federal regulation, and further liability in courts.
I am in now way saying there won't be some aftermarket company that comes out with a program, but if they did, they could become liable in case of an accident caused by the system not operating correctly, so will an aftermarket company come along and do a program?
Yes, an aftermarket company could have you sign a waiver, but will it be upheld in court? Or, let's say I obtain such program, and then I sell the vehicle and the next owner never checks his tire pressures and goes out on a Texas highway on a hot day, overloaded, and blows a tire, and kills half his family. He will sue me, but as soon as I disclose what company offered the reprogram, they will sue that company too. Easy to understand, it is called "deep pockets." That company will probably have deeper pockets than me.
Now, some are saying that if the sensors are removed, the system will not warn you of a sensor malfunction. I have not tried it, but my understanding it is should set of a TPM warning that the system is malfunctioning. Two things come to my mind on this:
1. The system is malfunctioning and the program needs repair. Something I hate to say I will note to the truck BCM programmer on Monday, if I see him. I do know that there have been two new programming releases since H3 inception. The programming notes say nothing about the TPM system, but who knows, maybe they slipped it in without notation.
2. Possibly, since no sensors are seen by the BCM, it faults to no TPM message, and keeps quiet. Possibly, at this time, the auto manufacturer believes they have followed the letter of the law, and if the customer so wishes, they can bypass the system, and if they have an accident due to the lack of sensor, the fault is theirs and GM has no legal obligation. Again, I'm not sure.
However, I find it easy to live with the system, even though I have had the early morning wake up that states the tire pressure is low.
Depening on where you live, the change in seasons will affect your tire pressure. If your tires were checked and air was added or removed when the ambient temps were around 80 degrees, and then as fall approaches, the ambients drop to around 40, your tires will be running approx. 4 lbs under recommended pressures. Then, one morning it drops to the 20s, and now you are running 6 lbs under.
So, if you get the warning on one of the first cold mornings in fall, and the message goes away after a mile or two, it generally means you need to adjust your TP to accomodate the fall in ambient temps. As you drive, the tires warm, and the TP will rise.
Biggest problems I see for people who do this are:
One, they will check the pressures after driving twenty miles, and the increase in TP can be up to 4 lbs due to the rise in the tires temp. That is why tire pressure should be check on a cold tire.
Another big problem is having the local oil change shop check your pressures after driving around all day long. Let's face it, these guys mean well, but are following some dumb instructions. They will look at your tire placard, and adjust your tire pressure to the recommended setting. However, these are hot tires, and they are in effect, reducing your recommended tire pressures.
So, I have driven around all day, and I pull into Uncle Ed's Oil Change (something I would never do). If my tires are set accurately on cold tires at 35 psi, they are probably now at 39 psi. Little Eddie equalizes the tire pressures to 35 psi and I leave.
Next morning, after the tires have cooled, they are now at 31 psi. So when the temps drop the sensors register low tire pressures and my system goes off.
The Federal regs allow up to a twenty percent drop in recommended pressure before a warning is to be issued. However, from my one experience, it appeared mine went off when the tires were at approx. 29-30 psi.
When the temps start to drop in the fall, I usually end up adding some air to all the tires to keep them at 35 psi. That way, it would take quite a drop at night to set off the warning.