Tire Pressure Monitoring System
Thread Starter
Senior Member
Joined: 10-02-2013
Posts: 145
From: Oklahoma
Tire Pressure Monitoring System
I've noticed something recently in my 2008 HHR SS and the TPMS. The two rear tires always seem to be 1 to 2 lbs lower than the front according to the TPMS report in the DIC. Even carefully filling each tire to, say, 32 lbss (according to the TPMS), it doesn't take long for the rears to show 31 lbs. while the fronts remain at 32 lbs.
I can't imagine leaks in the rears as they then remain steady at 30-31 but always 1-2 lbs. less than the fronts.
Not a big deal but just wondered if anyone else has noticed the same thing.
I can't imagine leaks in the rears as they then remain steady at 30-31 but always 1-2 lbs. less than the fronts.
Not a big deal but just wondered if anyone else has noticed the same thing.
Platinum Member
Joined: 12-06-2009
Posts: 11,721
From: Alabama
I have one that seems to show 1 lb. less on the DIC than from my hand gauge. Too close for me to worry about it.
Now I have noticed this. If you park it where only one side gets direct sunlight, the other side in shade. The sunny side will show higher pressures.
And, in the summer, drive a ways and watch the pressures increase 5-7 lbs..
Point being. All this has been going on before we had TPMS on cars. We just notice it because of the computers and DIC's on cars now.
Plus. The low profile SS tires are more sensitive to pressure changes because of the tire design.
I just try to not look at the DIC tire pressures too often. Makes my brain try to find a problem.
Now I have noticed this. If you park it where only one side gets direct sunlight, the other side in shade. The sunny side will show higher pressures.
And, in the summer, drive a ways and watch the pressures increase 5-7 lbs..
Point being. All this has been going on before we had TPMS on cars. We just notice it because of the computers and DIC's on cars now.
Plus. The low profile SS tires are more sensitive to pressure changes because of the tire design.
I just try to not look at the DIC tire pressures too often. Makes my brain try to find a problem.
Thread Starter
Senior Member
Joined: 10-02-2013
Posts: 145
From: Oklahoma
Know what you mean, LOL. Mine parks east-west and one might think the rears (most sun time) would be higher. I typically don't check mine that often. Maybe after extended cold or after a few miles into a long trip. Just something that struck me odd.
Senior Member
Joined: 12-24-2007
Posts: 2,873
From: Seville. OH
Here is a tsb from GM about tpm's. In the tsb it mentions temperature changes.
09-03-16-002
Service Information 2008 Chevrolet HHR | HHR (VIN A) Service Manual | Document ID: 2272292
--------------------------------------------------------------------------------
#09-03-16-002: Dealership Service Consultant Procedure as Vehicle Comes Into Service Drive for Tire Pressure Monitor (TPM) System Message, Light and Customer Information - (May 4, 2009)
Subject: Dealership Service Consultant Procedure as Vehicle Comes into Service Drive for Tire Pressure Monitor (TPM) System Message, Light and Customer Information
Models: 2006-2010 Cars and Light Duty Trucks (Including Saturn and Saab)
Attention: The information found in this bulletin is to be used as a dealership service consultant procedure for customers coming into the service lane with an illuminated "low tire light" or comments on a check tire pressure/low tire pressure/add air to tire or service tire monitor system message. Maintaining proper tire pressures is an Owner’s Maintenance item and is not covered under warranty.
--------------------------------------------------------------------------------
Customer Concerns and Confusion with the Tire Pressure Monitoring (TPM) System
The following procedure should be used by dealership service consultants when a customer comes into the service drive with a "low tire light" on or comments on a check tire pressure/low tire pressure/add air to tire or service tire monitor system message. The service consultant should perform the following steps:
Procedure
Turn the key to ON, without starting the engine.
• If the low tire light comes on and stays on solid with a check tire pressure/low tire pressure/add air to tire message (on vehicles equipped with DIC), advise the customer:
- The system is working properly.
- Properly adjusting all tire air pressures to the recommended levels and driving the vehicle will turn the light off (refer to the Tire and Loading Information label on the driver side door).
- More detailed information can be found in the Owner Manual.
- Service is not covered under warranty - this maintenance is the responsibility of the owner.
- Give the customer a copy of the attached "GM Customer TPMS Information".
• If the Tire Pressure Monitor (TPM) light blinks for one minute then stays on solid with a service tire monitor system message (on vehicles equipped with DIC):
- A TPM system problem exists. The vehicle should be written up accordingly and sent to your service department for further DTC diagnosis and service.
- If dashes (--) are displayed in only one or two of the tire pressure readouts, it is likely caused by a previous TPM system relearn that was performed incorrectly due to interference from another vehicle’s TPM system during the relearn process (refer to the Important statement later in this bulletin regarding TPM relearn with a Tech 2®).
- If dashes (--) are displayed in all four of the tire pressure readouts, there is a system problem. Follow the appropriate SI service procedures.
• If a customer indicates the low tire light comes on for a few minutes when the vehicle is started, then goes off after driving a while, advise the customer:
- The system is working properly.
- Most likely, air pressure in one or more of the tires is low enough to turn the light on when tires are cold. After driving for a while, tires will heat up, allowing tire air pressure to increase above the threshold causing the light to go off. Properly adjusting all tire air pressures to the recommended levels will correct this (Refer to the Tire and Loading Information Label on the driver side door).
- More detailed information can be found in the Owner Manual.
- Service is not covered under warranty - this maintenance is the responsibility of the owner.
- Give the customer a copy of the attached "GM Customer TPMS Information".
For more detailed information, refer to Corporate Bulletin Number 07-03-16-004 and TPMS Training Course 13044.12T2.
Tire Pressure Light
At key on, without starting the vehicle:
Steady Solid Glowing TPM Indicator
If the TPM indicator appears as a steady glowing yellow lamp (as above), the system is functioning properly and you should add air to the tires to correct this condition.
Blinking TPM Indicator
If the TPM indicator appears as a BLINKING yellow lamp for one minute and then stays on solid, diagnostic service is needed.
The Effect of Outside Temperature on Tire Pressures
Important: As a rule of thumb, tire pressure will change about 7 kPa (1 psi) for every 6°C (10°F) decrease in temperature - Tire pressure will drop when it gets colder outside, and rise when it gets warmer.
Under certain situations such as extreme outside temperature changes, the system may bring on a solid light with a check tire pressure message. This should be considered normal and the system is working properly. The light will turn off upon adding the proper amount of air to the tires (refer to the Tire & Loading Information label in the driver’s door opening). When properly adjusting tire air pressure, the following steps are important to help optimize the system and prolong bringing a tire pressure light on:
• Use an accurate, high quality tire pressure gauge.
• Never set the tire pressure below the specified placard value regardless of tire temperature or ambient temperature.
• Tire pressure should be set to the specified placard pressure at the lowest seasonal temperature the vehicle will encounter during operation.
• When adding proper tire air pressure, it is important to remember fluctuations in outside air temperatures and tire temperatures effect tire air pressures.
• After you have added the proper tire pressure, if the vehicle has a DIC (after the system has updated), check to see if DIC displays are the same readings as the tire pressure gauge used (adjust as necessary).
• Only perform a TPM sensor re-learn after a tire rotation or system part replacements and use the Tech 2® to initiate the relearn whenever possible to avoid invalid sensor I.D. learns.
Important: Always take outside temperature and tire temperature into consideration to properly set tire pressures. For example, on colder days (20°F/-7°C), if setting the tire pressure when the vehicle has been indoors (60°F/16°C) or the tires are warm from being driven, it will be necessary to compensate for the low outside temperature by adding 21-27 kPa (3-4 psi) more than the placard pressure. At some later time, when the vehicle has been parked outside for a while, the tires will cool off and the pressures will drop back into the placard range.
Important: Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile racing. Tires inflated with nitrogen gas may exhibit less of a pressure change in response to outside temperature changes. Nitrogen gas inflation is compatible with GM TPM sensors. For additional information, refer to Corporate Service Bulletin 05-03-10-020B.
Important: All Models (except the Pontiac Vibe): Each tire monitor sensor is learned to a specific vehicle corner. When performing a TPM relearn (only after a tire rotation or replacement of a TPM sensor or module), always use the Tech 2® to initiate the J 46079 relearn process. Tech 2®-initiated relearns lock out other vehicle TPM signals that may be broadcasting in the area. Only signals initiated by the J 46079 tool will be accepted. This method avoids storing false TPM I.D.s and will prevent customers from returning with dashes (--) displayed in tire pressure readouts and/or a flashing tire pressure monitor (TPM) light. Checking the four TPM I.D.s with the Tech 2® prior to and following relearn to verify they are the same can prevent invalid I.D. learns.
Customer TPMS Information
Dear GM Customer:
Customer care is at the top of our priority list at GM. We value our customers and want to make certain of a great ownership experience. To assist you in better understanding your vehicle, please make note of the following information relative to tire air pressure and the vehicle system that monitors air pressure performance.
Tire air pressure is a maintenance item in which the owner is responsible. Your vehicle is equipped with a Tire Pressure Monitoring System (TPMS) designed to provide you with adequate information to maintain proper tire air pressure. Proper tire air pressure is important to optimize safety, fuel economy, vehicle performance, and tire wear.
Changes in weather, including warm or cold outdoor temperatures, can cause air in your tires to expand or contract. Should this occur, your vehicle’s TPMS may give you a low tire signal/alert along with the following message: Check Tire Pressure/Low Tire Pressure/Add Air To Tire.
Your GM Dealer has determined that the TPMS on your vehicle is working properly. The light will turn off upon adding the proper amount of air to the tires (per the Tire & Loading Information label in the driver’s door opening) followed by driving the vehicle a short distance. The low tire light is similar to the low fuel indicator and adding fuel or air to the vehicle will turn off the light.
For more information, refer to the Owner Manual or go to www.CheckMyTires.org.
09-03-16-002
Service Information 2008 Chevrolet HHR | HHR (VIN A) Service Manual | Document ID: 2272292
--------------------------------------------------------------------------------
#09-03-16-002: Dealership Service Consultant Procedure as Vehicle Comes Into Service Drive for Tire Pressure Monitor (TPM) System Message, Light and Customer Information - (May 4, 2009)
Subject: Dealership Service Consultant Procedure as Vehicle Comes into Service Drive for Tire Pressure Monitor (TPM) System Message, Light and Customer Information
Models: 2006-2010 Cars and Light Duty Trucks (Including Saturn and Saab)
Attention: The information found in this bulletin is to be used as a dealership service consultant procedure for customers coming into the service lane with an illuminated "low tire light" or comments on a check tire pressure/low tire pressure/add air to tire or service tire monitor system message. Maintaining proper tire pressures is an Owner’s Maintenance item and is not covered under warranty.
--------------------------------------------------------------------------------
Customer Concerns and Confusion with the Tire Pressure Monitoring (TPM) System
The following procedure should be used by dealership service consultants when a customer comes into the service drive with a "low tire light" on or comments on a check tire pressure/low tire pressure/add air to tire or service tire monitor system message. The service consultant should perform the following steps:
Procedure
Turn the key to ON, without starting the engine.
• If the low tire light comes on and stays on solid with a check tire pressure/low tire pressure/add air to tire message (on vehicles equipped with DIC), advise the customer:
- The system is working properly.
- Properly adjusting all tire air pressures to the recommended levels and driving the vehicle will turn the light off (refer to the Tire and Loading Information label on the driver side door).
- More detailed information can be found in the Owner Manual.
- Service is not covered under warranty - this maintenance is the responsibility of the owner.
- Give the customer a copy of the attached "GM Customer TPMS Information".
• If the Tire Pressure Monitor (TPM) light blinks for one minute then stays on solid with a service tire monitor system message (on vehicles equipped with DIC):
- A TPM system problem exists. The vehicle should be written up accordingly and sent to your service department for further DTC diagnosis and service.
- If dashes (--) are displayed in only one or two of the tire pressure readouts, it is likely caused by a previous TPM system relearn that was performed incorrectly due to interference from another vehicle’s TPM system during the relearn process (refer to the Important statement later in this bulletin regarding TPM relearn with a Tech 2®).
- If dashes (--) are displayed in all four of the tire pressure readouts, there is a system problem. Follow the appropriate SI service procedures.
• If a customer indicates the low tire light comes on for a few minutes when the vehicle is started, then goes off after driving a while, advise the customer:
- The system is working properly.
- Most likely, air pressure in one or more of the tires is low enough to turn the light on when tires are cold. After driving for a while, tires will heat up, allowing tire air pressure to increase above the threshold causing the light to go off. Properly adjusting all tire air pressures to the recommended levels will correct this (Refer to the Tire and Loading Information Label on the driver side door).
- More detailed information can be found in the Owner Manual.
- Service is not covered under warranty - this maintenance is the responsibility of the owner.
- Give the customer a copy of the attached "GM Customer TPMS Information".
For more detailed information, refer to Corporate Bulletin Number 07-03-16-004 and TPMS Training Course 13044.12T2.
Tire Pressure Light
At key on, without starting the vehicle:
Steady Solid Glowing TPM Indicator
If the TPM indicator appears as a steady glowing yellow lamp (as above), the system is functioning properly and you should add air to the tires to correct this condition.
Blinking TPM Indicator
If the TPM indicator appears as a BLINKING yellow lamp for one minute and then stays on solid, diagnostic service is needed.
The Effect of Outside Temperature on Tire Pressures
Important: As a rule of thumb, tire pressure will change about 7 kPa (1 psi) for every 6°C (10°F) decrease in temperature - Tire pressure will drop when it gets colder outside, and rise when it gets warmer.
Under certain situations such as extreme outside temperature changes, the system may bring on a solid light with a check tire pressure message. This should be considered normal and the system is working properly. The light will turn off upon adding the proper amount of air to the tires (refer to the Tire & Loading Information label in the driver’s door opening). When properly adjusting tire air pressure, the following steps are important to help optimize the system and prolong bringing a tire pressure light on:
• Use an accurate, high quality tire pressure gauge.
• Never set the tire pressure below the specified placard value regardless of tire temperature or ambient temperature.
• Tire pressure should be set to the specified placard pressure at the lowest seasonal temperature the vehicle will encounter during operation.
• When adding proper tire air pressure, it is important to remember fluctuations in outside air temperatures and tire temperatures effect tire air pressures.
• After you have added the proper tire pressure, if the vehicle has a DIC (after the system has updated), check to see if DIC displays are the same readings as the tire pressure gauge used (adjust as necessary).
• Only perform a TPM sensor re-learn after a tire rotation or system part replacements and use the Tech 2® to initiate the relearn whenever possible to avoid invalid sensor I.D. learns.
Important: Always take outside temperature and tire temperature into consideration to properly set tire pressures. For example, on colder days (20°F/-7°C), if setting the tire pressure when the vehicle has been indoors (60°F/16°C) or the tires are warm from being driven, it will be necessary to compensate for the low outside temperature by adding 21-27 kPa (3-4 psi) more than the placard pressure. At some later time, when the vehicle has been parked outside for a while, the tires will cool off and the pressures will drop back into the placard range.
Important: Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile racing. Tires inflated with nitrogen gas may exhibit less of a pressure change in response to outside temperature changes. Nitrogen gas inflation is compatible with GM TPM sensors. For additional information, refer to Corporate Service Bulletin 05-03-10-020B.
Important: All Models (except the Pontiac Vibe): Each tire monitor sensor is learned to a specific vehicle corner. When performing a TPM relearn (only after a tire rotation or replacement of a TPM sensor or module), always use the Tech 2® to initiate the J 46079 relearn process. Tech 2®-initiated relearns lock out other vehicle TPM signals that may be broadcasting in the area. Only signals initiated by the J 46079 tool will be accepted. This method avoids storing false TPM I.D.s and will prevent customers from returning with dashes (--) displayed in tire pressure readouts and/or a flashing tire pressure monitor (TPM) light. Checking the four TPM I.D.s with the Tech 2® prior to and following relearn to verify they are the same can prevent invalid I.D. learns.
Customer TPMS Information
Dear GM Customer:
Customer care is at the top of our priority list at GM. We value our customers and want to make certain of a great ownership experience. To assist you in better understanding your vehicle, please make note of the following information relative to tire air pressure and the vehicle system that monitors air pressure performance.
Tire air pressure is a maintenance item in which the owner is responsible. Your vehicle is equipped with a Tire Pressure Monitoring System (TPMS) designed to provide you with adequate information to maintain proper tire air pressure. Proper tire air pressure is important to optimize safety, fuel economy, vehicle performance, and tire wear.
Changes in weather, including warm or cold outdoor temperatures, can cause air in your tires to expand or contract. Should this occur, your vehicle’s TPMS may give you a low tire signal/alert along with the following message: Check Tire Pressure/Low Tire Pressure/Add Air To Tire.
Your GM Dealer has determined that the TPMS on your vehicle is working properly. The light will turn off upon adding the proper amount of air to the tires (per the Tire & Loading Information label in the driver’s door opening) followed by driving the vehicle a short distance. The low tire light is similar to the low fuel indicator and adding fuel or air to the vehicle will turn off the light.
For more information, refer to the Owner Manual or go to www.CheckMyTires.org.
Senior Member
Joined: 09-25-2011
Posts: 457
From: Towson
These things are really crap. I've replaced 3 of them since 2011. One time one showed I had 63 lbs of pressure, a few seconds later it showed 24 lbs of pressure, then the dreaded lines come on the the TPMS light starts blinking. I test mine with a digital gauge before putting air in the tires. I will be riding along just fine and then, "BAM", TPMS service light starts blinking, even with an extended warranty it costs me $100 for deductible every time I need to replace them. I hate them ! 
Moderator
Joined: 01-23-2009
Posts: 26,532
From: Fredericksburg,VA
These things are really crap. I've replaced 3 of them since 2011. One time one showed I had 63 lbs of pressure, a few seconds later it showed 24 lbs of pressure, then the dreaded lines come on the the TPMS light starts blinking. I test mine with a digital gauge before putting air in the tires. I will be riding along just fine and then, "BAM", TPMS service light starts blinking, even with an extended warranty it costs me $100 for deductible every time I need to replace them. I hate them !
So, your extended warranty only covers about $19 per sending unit? And it's probably not the actual problem.
Most of the time, simply restarting the car will get the display back to normal if it is just one of the tires. That comes from RF interference.
You are the very first to cite repeated replacement of sending units.
Senior Member
Joined: 03-30-2009
Posts: 185
From: wheeling
tire pressure sensor failures are VERY COMMON on german cars. i know - i work for an extended warranty company for 12 years. on all other brands, they simple dont' register w/ the scan tool at the dealer, so they don't know if the sensor shorted or the battery went dead, so we pay the repair claim. but, on german cars. it actually shows battery voltage on their scan tool & it's always a battery failure & batteries are NOT COVERED - so, we deny the claim. we get LOTS of calls on german cars - esp. VW brands.
