Tuesday, June 18, 2013

2008 and newer General Motors Tire Monitor Fix.

When dealing with tires or anything relating to same, refer to the owners manual as well as the tire placard on the inside of the driver's door. The van we'll be dealing with is a 2008 Chevrolet Express 2500 (3/4 ton). Incorrect tire pressures can result in excess fuel consumption, excess wear, poor handling, tire failure as well as injury up to and including death and of course property damage. It is the responsibility of the owner as well as qualified service personnel to make sure that proper procedures for tire servicing are followed. Vehicle manufacturers, (save for the van in question, which has been the same look since 2003, but the dash was redone in 2008) can and do change their designs and can render this obsolete. Tire pressures must be checked when they are cold or the readings will be inaccurate. "Cold" means driven less than a mile if at all humanly possible. Do this and any other fixes at your own risk.

GM has had the GMC Savanna and Chevy Express in their current configuration since 2003. Only minor changes to the dashboard, some electronics and steering wheel changed in 2008. This is also when the United States mandated tire pressure monitoring systems in every new vehicle. The Express is my work truck with 130,000 miles . The tire pressure monitoring system is pretty durable even though it seem to confound mechanics in my neck of the woods.  Every time I go to get the tires rotated or like last week, replaced it seems like it's a sure thing that I'll be staring at the tire pressure warning light. It's a yellow light with the cross section of a tire and an exclamation point. In addition, the message center / odometer will send you the GM equivalent of "warning Will Robinson!"

After talking to the mechanic who said he needed two hours to reset this monstrosity with a special scanner, I read the owners manual. These have a wealth of information, including how to initialize this system. To really understand, you need to know how this works. There is a sensor in each wheel and each sensor has a radio transmitter (guessing here) with a unique identification. The body control module (again, guessing to over generalizing) is programmed with the parameters including the required tire pressures of each wheel. In the case of said 2008 Chevy Express 2500, the pressures are 50 p.s.i. in front and 80 p.s.i. in the rear. The computer cannot "see" where the tires are at relative to where they are on the vehicle, so there is a procedure to get it to recognize each tire by the ID number in the sensor. The computer "reads" this in a set sequence that the computer and user understand. Unless a battery is low or a sensor needs replacement, you do not need a scan tool to reset these. You do need a key to push the valve core to let air out, a high pressure air hose to let air in, and a few minutes.

All you need to do is start the engine and notice there are four buttons stacked to the left of the gauges. The only two you need initially are the one on the bottom with the check mark and the second one from the top with a picture of a car. Read these a couple times first and commit to memory as the time will be limited once you start. Roll down the window and close the door. The transmission needs to be in park and the parking brake set. Reach through the window from the outside and push the button with the car on it until "push (check mark button) to relearn tire positions" appears. Push the check mark button and the horn will chirp. Let out or add air to each tire, starting with the left front, right front, right rear and ending with the left rear. You are walking counterclockwise as seen from the top of the vehicle. When the computer recognizes the tire, the horn will chirp and will be your cue to move to the next wheel. When the left rear wheel is done, the horn will chirp.  Set the tires to the correct pressure and confirm their positions on the dashboard info center by pushing the top button until it shows the tire positions and the pressures. The tire pressure light should also be out. as long as you are satisfied with your results, put the caps back on and let someone else use the air hose. Maranatha!

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