quote:
ORIGINAL: jpac4lyf
this is great info... I'm planning on faxing your advice to the dealer as we speak to help my truck if not others too.
So, in the grand scheme of things when I get my H3 back from the dealer tomorrow due to the Tire Pressure alert, how concerned should I be if on Friday the damn TPMS light comes on again?? Do you feel as long as I gauge the pressure on my own all is well... or do you feel like the dealer should keep it til they get the thing right? The 07 H3 is only 4 weeks old after all? They are working on my pressure issue right now in Scottsdale!
We had some early on problems with early 06 H3s, but primarily most of the problems were due to incorrect tire pressure and fluctuating temps. Example, if your recommended TP is 35 cold, and in July it was set to 35 on a cold tire. Then along comes the fall in November, warm days, cold nights. Your tire will lose 1 psi for ever 10 degree drop in temp; therefore, if the tire was set on a 90 degree day, and it is now 40 and at night it dropped to 30, you are now 6 psi under. Therefore, if you start the vehicle at 30 degrees, the TP low signal comes on, and you drive a few miles and the warning goes off, it means the tires have warmed, pressure increased and pressure now exceeds the set point to set off a sensor.
That is how it works in a perfect world. If the dealer spends some time, the system can be diagnosed. Depends on how much time the dealer wants to spend. Primarily there are two unique messages that may be outputted. One is something like "check tire pressures" which implies a sensors sees a low tire. The other is something like service the tire pressure system or tire monitor, and means there is a fault in the system.
Usually the check tire pressures means there is a low tire, that may have increased in pressure on the drive to the dealership in the day. The other warning message indicates there is a problem with the system, and this could be a sensor, BCM calibration or a BCM.
A few points to always remember about this TP system, or any other system used by any other manufacturer.
1. Always check tire pressures on cold tires. Cold not meaning ambient temps, but a tire that has not been driven in over three hours.
2. Make sure there is NO sunlight shining on a tire or tires. Direct sunlight can raise TP by up to 2 psi.
3. Check pressures every month or sooner if there is a drastic weather change (global warming or an instant ice age
)
4. If rotating the four tires on the ground, no need to reprogram these sensors. (If you have a corner specific system like on a Cadillac or Vette, etc., you do need to learn for each corner. However, the system will not know you rotated the tires, it would just output the wrong information for which tire is low. Or in the case of some, you can push a button and see the TP for any of the four tires.)
5. If rotating with a spare, you must put the BCM into program mode and program the four on the ground. If not, the spare that is now on the ground will not be read by the BCM, and the BCM will continue to read the new spare.
6. If you get a sudden cold wave, and you get a low tire pressure warning in the morning that goes away after driving, it is low pressure due to a change in temps. Time to recheck the pressures.
7. If off-roading and you lower your TP, you will have to ignore the message and warnings. I made a suggestion, at the request of someone online, about turning off the system if the t/case is put into 4-wheel low lock. GM will not do this due to the liability. This is a Federal requirement, thanks to Ford/Bridgestone-Firestone, and primarily thanks to those people who ran tires too low, with overloaded Explorers, in extreme warm conditions that caused a tire to explode, rolling the Explorer and killing someone.
As for your specific problem, I'm not there so I can't say. If it were ME, and I knew the pressures w
