2008 Tire Pressure Monitoring Sensors

[march]

How do I deal with the TPMS system on a 2008 Cobalt?
I plan to remove the 4 stock wheels w/ sensors to install 4 steel wheels w/ snow tires. The snows don't have TPMS's.

-What does the car do while running w/ no sensors for 2 months?
-Do I need to re-calibrate the system in the spring when the stock wheels are re-installed?
If so, how?

[Montecarloman]

What you could do is swap the sensors into the winter tires. If you don’t wish to do that then you'll have a constant Low pressure light and depending on the programming may not allow you to drive over a certain MPH. Corvettes are limited in such a way, when the pressure is too low the computer puts the car in reduced handling mode. There is a way to recompensate the sensors without special tools in some cars, but it depends on the car and year.

[march]

The reason why I ask is:
-The dealer told me that I'll just get 1-2 idiot lights by doing so, but the owner's manual states that the Driver Info Center will display an error every time the car starts. That seems to indicate that it will need to be reset every time the car starts.

I'm just wondering what those of you who bought new wheels have found on an 08 Cobalt, when you didn't transfer the sensors.
I guess I could try it, but I don't want to end up bringing the car back to the dealer to reset something if I do.

[Montecarloman]

With GM systems all you need to do is keep straight which tire/wheel goes where on the car. When you bolt the wheels back on the car and drive it the system will re-sync and show proper pressure. The reset is required when you do a rotation or replace a sensor so the computer knows which tire/wheel is on which corner of the car. I am fairly sure the corvette is the only one with a reduced handling function.

[blkbalt06]

which models have the TPMS? i didnt even know about this!

[WolfmanDave]

Originally Posted by Montecarloman

I am fairly sure the corvette is the only one with a reduced handling function.

I don't know about the Corvette, but none of the Cadillacs have that kind of programming. I work with these TPMS sensors everyday. There is a specific tool we use to make the system "relearn" the position of the sensors. As stated before, one of the times this is needed is if you rotate the tires. It is also necessary if battery power was removed and certain system glitches may also make the system lose the psi readings and positions.

As far as your situation, you can put winter tires on your car without sensors, you'll just have the TPMS warning light always lit. This light will not be able to be turned off until you return the wheels with sensors back to the car. And if you don't put those sensors in their exact positions, the readings won't be correct. So, either mark them as you take them off, or see your dealer immediately after re-mounting them. And I wouldn't worry about the TPMS warning light affecting your handling.

Any other questions, let me know.

WolfmanDave added 7 Minutes and 51 Seconds later...

Originally Posted by blkbalt06

which models have the TPMS? i didnt even know about this!

'08+. The TREAD Act of 2000 required TPMS sensors on, I think, 20% of vehicles by 2004, 80% of vehicles by 2006, and 100% of vehicles by 2008 model years.

[march]

That's very helpful.
Thank-you...

march added 20 Minutes and 35 Seconds later...

Originally Posted by blkbalt06

which models have the TPMS? i didnt even know about this!

Only the 2008 Cobalts have this system.
Here is some information from OnStar, although the comments I've received here are more useful:

General Tire Pressure Information
Your tires need the correct amount of air pressure to help ensure optimum handling, fuel economy, tread life, and ride comfort. Tire pressure will vary up to 5 psi, depending on the temperature of the air in and around your tire and how much it has recently been driven. It is best to check your tires while they are "cold" against the manufacturer's recommended pressure levels.
Each month, OnStar retrieves tire pressure information from the Tire Pressure Monitoring System in your vehicle and displays details in your OnStar Vehicle Diagnostics email. Since OnStar cannot confirm that these readings are always from a "cold" tire, you may see variation from month to month in your readings, and you should confirm pressures on each tire before adjusting them. If we detect a tire pressure reading that is outside of the manufacturers recommended range, the tire status will be changed from green to yellow or red.

Status: Diagnostic: Action:
Tire Pressure Monitoring: Normal No maintenance needed. Your tires are inflated in the proper range to ensure optimum performance and fuel economy.
Tire Pressure Monitoring: Low One or more of your tires may need attention. At your next fuel fill-up, check all your tires for proper inflation. Underinflated tires can cause:
Premature or irregular wear
Poor handling
Reduced fuel economy

Tire Pressure Monitoring: -- This information may be missing due to a communications error that prevented OnStar from retrieving your tire pressure data.
If there is a message in your Digital Information Center to 'service tire pressure monitoring system', then you cannot rely on tire pressure monitoring or the OnStar system to alert you that your tires are improperly inflated. The cause of this situation could be:

The factory-installed wheels have been replaced with wheels that do not have compatible sensors.
The pressure sensors in your factory installed wheels are not functioning properly.
Refer to your owner's manual for further information.

Tire Pressure Monitoring: Low One or more of your tires requires immediate attention to ensure safe vehicle operation. Please check all your tires for proper inflation as soon as possible. Underinflated tires can cause:
Premature or irregular wear
Tire failure
Poor handling
Reduced fuel economy

Tire Pressure Monitoring: High One or more of your tires requires immediate attention to ensure safe vehicle operation. Please check all your tires for proper inflation as soon as possible. Overinflated tires can cause:
Unusual wear
Poor handling
Rough ride


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Tire Pressure Monitoring System
Your vehicle is equipped with a Tire Pressure Monitor System (TPMS), which uses radio and sensor technology to check tire pressure levels in each of your installed tires. TPMS sensors monitor the air pressure in your vehicle's tires and transmit tire pressure readings to a receiver located in the vehicle. The TPMS is designed to alert the driver if a low tire pressure condition exists, and may also allow the driver to check tire pressure levels using the Driver Information Center (DIC).

When Your Vehicle Telltale Is On Continuously
One or more of your tires is significantly underinflated and requires immediate attention. Correct your tire pressures as soon as possible. It is not necessary to visit your dealer. Correcting the tire pressures will cause this light to go out (much like adding fuel to your vehicle causes your yellow Low Fuel light to go out.)

When Your Vehicle Telltale Flashes, And Then Is On Continuously
You may have a problem with your Tire Pressure Monitoring System. See your dealer for service.

If you have replaced your factory-installed tires or wheels, your TPM system may not be functioning properly. Check with your installer for compatibility.


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Rotating Your Tires
If you rotate your own tires or have them serviced at a facility that is not an authorized GM repair center, you should make sure that the tire pressure sensors are reset as outlined in your owner's guide. This will insure that the sensors in each tire represent the new tire positions. If this procedure is not followed it is likely that the readings in your OnStar Diagnostics Email and on the display in your vehicle may indicate the incorrect tire locations.


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Tire Pressure and Changing Temperatures
Tire pressure can change over time as temperature changes. The pressure goes up as temperature goes up, and pressure goes down as temperature goes down. (A good rule of thumb is 1 psi for every 10°F.)

This can happen seasonally (from summer into fall), daily (from a cold night to a warmer afternoon), and while driving (the tires warm up as you drive).

You may notice during cooler weather conditions that the Low Tire Pressure indicator will appear when the vehicle is first started and then turn off as you start to drive. This is an early indicator that the pressure is getting low and tires need to be inflated to the proper pressure.



Low Tire Pressure Indicator


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Tire Pressure and Fuel Economy
Keeping your tires properly inflated can save up to 3% on gas mileage. For every 1 psi drop in pressure for all tires, drop your vehicle's gas mileage by 0.4%.


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Checking Your Tires
Tire pressure should be checked monthly and should only be adjusted on cold tires (when your vehicle has been parked for at least three hours or driven less than one mile).

Tire pressure information can be found on the tire placard, which is located on the pillar of the driver's door. Do NOT inflate the tires to the pressure value shown on your tire sidewall - that value is the Maximum Inflation Pressure for the tire. Your tire pressures should match the Cold Inflation Pressure shown on the placard label inside your front driver's door pillar.



Sample Tire Placard

Use a good-quality pocket-type gauge to check tire pressure. You cannot tell if your tires are properly inflated simply by looking at them. Radial tires may look properly inflated even when they're underinflated.

Remove the valve cap from the tire valve stem. Press the tire gauge firmly onto the valve to get a pressure measurement. If the inflation pressure matches the Cold Tire Pressure on the Tire and Loading Information label, no further adjustment is necessary. If the inflation pressure is low, add air until you reach the recommended amount. If you overfill the tire, release air by pushing on the metal stem in the center of the tire valve until you reach the recommended amount. Recheck the tire pressure with the tire gauge. Be sure to put the valve caps back on the valve stems. They help prevent leaks by keeping out dirt and moisture. As always refer to your vehicle's owner's manual for more detailed information on tire maintenance.

thus is why I will never buy a new car again...

I dispise electronic nannys... traction control... auto lights... tire crap... it's taking the thinking out of driving... and is very dangerous...

[fatcobalt08]

you could just take the wheels to a discount tire and have them remove the sensors from the stock and place them in your snow ones and they have a tool to reset them to where they are on the vehicle i know i work there. not sure how much they charge they seeing as i dont deal with sales

[march]

Originally Posted by fatcobalt08

you could just take the wheels to a discount tire and have them remove the sensors from the stock and place them in your snow ones and they have a tool to reset them to where they are on the vehicle i know i work there. not sure how much they charge they seeing as i dont deal with sales

That would cost about $40+tax to re-mount & balance 4 snow tires on wheels, then another $40+tax in 2 months to re-mount & balance the 4 all-season tires on the wheels they're currently on. I could also buy 4 additional wheel sensors for about $100 on e-bay.

Rather than spend around $100 or more for 2 months w/ no idiot light I mounted the 4 snow tires w/ no sensors. After driving the car for about 10 miles, the idiot light went off on the dash and a message appeared on the Driver Information Center (DIC). This happens every time the car starts, but is easily remedied by temporarily covering up the idiot light until I put the other tires/wheels back on. The DIC message is remedied by depressing 1 button on the steering wheel.

This was the dealer's recommended solution, and it seems to work fine. The idiot light won't bother anything and the TPMS can be reset in the spring, if necessary under the warranty, but that may not be necessary if I put the wheels back where they came from.