ketcat, now I understand. If you want the TPM system to work properly, I would suggest a different dealer to repair the issue. The system is actually quite simple, and a GOOD tech can repair the problem.
The larger tires will reflect set a message, if pressures are low, due to the higher volume of air inside the tire.
However, the system only uses five sensors (spare not recognized until on a corner), the BCM and the IPC to display the message. Most of the problems are due to a actual low pressures, or pressures variation between a warm day and a very cold night. In addition, dealers are being hit with people who never check their air pressures, so from warm weather to cold weather the system will go on since there is an approx. 1 psi drop for every 10 degrees.
The people who visit this site are smart enough to check their pressures, but the dealers don't know that. Some dealers automatically assume the person is one of those who does not check pressures.
I would demand the dealer to explain why they cannot fix the system, since for those on this site who say the system does not operate, there are hundreds more for each one who does not have a problem. Last resort, call the customer assistance center and complain. If it was happening to me, I would be furious too.
One bad sensor, could be the problem, a bad BCM could also cause a problem, but less likely.
As for programming the system, the dealer, nor I, can program in different parameters. This system is required by Federal Law, and GM will not allow reprogramming by a dealer, and even if they could, most dealers will not accept liability to reprogram in a different setting. (All vehicles will have this system by fall of next year, the Feds allowed them to be phased in over a period of time, and GM, like all manufacturers is installing the system on all new vehicle first, then redesign them on existing vehicles to meet the law.)
I do not believe there is a tire size bit to flip via the Tech 2. I guess I should take a look someday to verify this, but I have been told there is not a way to reprogram for a different size tire.
However, a 1" tire size increase between the 32 stock and the 33 off-road package, will not show that much on the speedo or odo, and keeps the speed and odometer within Federal requirements.
Again, my suggestion would be to get a dealer to fix the system. We all will have to live with the message when off-roading with reduced tires. Someone on this site (I believe it was Paragon) made a great recommendation to program the BCM to turn off the TPM system if the vehicle was in 4-LO Lock. I made this suggestion to someone at GM, and it didn't go over very well. I guess someone at GM (did I say attorney
), has reason to assume that there are idiots out there who would actually drive at a constant 40 mph, on a very hot day, and blow a tire. I hate to add, that they are probably correct in this assumption. (Actually met one that would be a candidate last year in Utah. Thought he could go where I had just been with an Chevy (ALL-WHEEL drive) Equinox with low ground clearance. I should have charged him for pulling him off the rocks, but just made him attach the tow rope to his vehicle.
As for the locker override...well, if a person understands electrical schematics, there might possibly be a way to override the locker. But this does not mean I know, or even imply that it can be done, or should be done, or has been done, etc.
