OBD Scanners & Tire Pressure (TPMS)

[SEMIJim]

Hi There,

It seems do odd to me that

• Any kind of analysis/performance tool would not be able to monitor/read tire pressure
  
  
• That there's so little definitive information on this subject
  
  

So, after having the "check engine" idiot light come on, yesterday, I thought "Maybe I'll finally get me an OBD scanner."

Thing that's held me off, so far, is the question of "But can/will it tell me my tire pressures?"

So, there's the question: Can any OBD scanner (preferable a Bluetooth version that'll talk to my Android phone and tablet) read/display tire pressure?

Thanks,
Jim

 

[dmanns67]

TPMS is a separate system. If your vehicle is not equipped with the system and TPMS sensors in the tires, you will not be able to monitor tire pressure via the DIC. I believe the TPMS system was introduced in 2006 on our platforms. Open the glove box and look at your build data plate. If you have the TPMS system, the RPO code will be UJ6.

I have the TPMS and even with the OBDII adapter, I cannot see tire pressure, only with the DIC. Without the DIC, all you would see on the dash is the TPMS light come on warning you that one or more tires have 25% lower air pressure than what is recommended.

However, there are after market systems that you can purchase. You will get (4) tire pressure sensors and a stand alone unit that can monitor the pressure wirelessly. I have seen them for as cheap as $100 and up to $300. Some of the aftermarket systems use actual TPMS sensors and others have sensors that install in place of the valve caps.

TPMS can be a PITA sometimes, but is a valuable system to have. It has saved my a$$ twice while on long road trips. Gives you enough warning to find a safe place to pull over.

 

[SEMIJim]

Without the DIC, all you would see on the dash is the TPMS light come on warning you that one or more tires have 25% lower air pressure than what is recommended.

....

TPMS can be a PITA sometimes, but is a valuable system to have. It has saved my a$$ twice while on long road trips. Gives you enough warning to find a safe place to pull over.

It also lights when you have too much tire pressure on any tire. Problem is: Without the ability to see what's up: You cannot tell if it's simply a tire that's a bit too low or too high, or sudden deflation due to a puncture.

Thus my interest in a scanner that can tell me tire pressure. If none can do it, I guess I'll just take a pass.

Thanks,
Jim

 

[neohio]

I have an old Snap-on red brick scanner. If I recall correctly, It will show the TPMS info. I believe you can even put the truck into TPMS learn mode. I know my Solus does it. but I want to say the old red brick will do it as well.

 

[dmanns67]

I should have noted that I was referring to the cheaper ELM327 OBDII wireless scan tool. A higher end scan tool might have the ability to read the TPMS, that's if the vehicle was equipped with the system from the factory.

SEMI, have you checked to see if your vehicle was equipped with TPMS from the factory based on the RPO code? That would be the place to start Also, I have never heard/had the TPMS light on the dash for over-inflation. If that was the case, then my light would always be on the dash because I run higher pressure than what is on the inside of the door.

The purpose behind the TPMS design is to warn for under inflation. For fuel economy, tire wear, and safety related reasons. I have read that the TPMS can also monitor temperature inside of the tires as well, maybe on higher end vehicles. Over inflation could shorten the life of tire tread and cause safety issues as well.

 

[SEMIJim]

A higher end scan tool might have the ability to read the TPMS, that's if the vehicle was equipped with the system from the factory.

SEMI, have you checked to see if your vehicle was equipped with TPMS from the factory based on the RPO code?

I always run mine over-inflated, as well. Came that way when I bought the truck, I asked about it here, and a number of people do. 36 psi all around.

When I got the truck I found the tires at 38 psi all around. I found that, on a blacktop expressway, at expressway speeds, in the summertime, when the sun's out: That 38 psi can climb far enough to trigger the system. I had the dash light come on, activated On Star (which I had at the time) and they told me what was up. I dropped a couple psi from each tire and was not bothered by that again.

As for reading the TPMS' data: From reading: I'm coming to believe that's a function of the software, rather than the scanner, for the Bluetooth devices--such as the ELM327 and OBDLink products. Further: It seems those are proprietary codes. Apparently software such as Torque can read them, and display them sensibly, if you know the manufacturer's/vehicle's PID(s) for the sensors and what the values mean.

Do I know if it's a factory TPMS system? Well, not for certain. Would a non-factory system communicate with the car's systems, such as it would light the dash idiot light, ring the "bell," and On Star could query the values?

Jim

 

[bobdec]

Your '07 should have a factory system.. The dash indicator and the DIC (if equipped) are a warning indication. More expensive scanners have the TPM communication ability and PID (Program ID) values. Or you could buy a standalone TPM pressure monitor but have to insure it will communicate with a GM TPM sensors. They actually read the TPM sensor RF signals directly. Back to scanners, unfortunately the TPM PID's are proprietary and GM charges the scan vendors $$$ for PID info and update Subscriptions, therefore they are not publicly available. As mentioned in previous posts if you can find the PID's you can enter them into the low cost Torque app.

Below is a cut/past from the Service Manual. The complete 20 page TPM description is available in the 2008 services manual in the sticky located here http://gmtnation.com/forums/topic/361-need-service-manuals-get-them-here/ the file is (TIRE PRESSURE MONITORING.pdf)


TIRE PRESSURE MONITOR DESCRIPTION & OPERATION

The tire pressure monitor (TPM) system warns the driver when a significant loss, or gain of tire pressure occurs
in any of the 4 tires and allows the driver to display the individual tire pressures and their locations on the driver
information center (DIC).
The system uses the instrument panel cluster (IPC), DIC, powertrain control module (PCM), lift gate module
(LGM), a radio frequency (RF) transmitting pressure sensor in each wheel/tire assembly, and the serial data
circuit to perform the system functions. Each sensor has an internal power supply with a 10 year service life.
When the vehicle is stationary, the sensors internal accelerometer is inactive, which puts the sensors into a
stationary state. In this state the sensors sample tire pressure once every 30 seconds and do not transmit at all if
the tire pressure does not change. As vehicle speed increases, centrifugal force activates the sensors internal
accelerometer causing the sensors to go into rolling mode. In this mode, the sensors sample tire pressure once
every 30 seconds and transmit in rolling mode once every 60 seconds. The LGM receives and translates the data
contained in each sensors RF transmission into sensor presence, sensor mode, and tire pressure. The LGM sends
the tire pressure and tire location data to the DIC via the serial data circuit.
The sensors continuously compare their last pressure sample to their current pressure sample and will transmit
in re-measure mode if a 8.3 kPa (1.2 psi) change in tire pressure has been detected in either a stationary or
rolling state. When the TPM system detects a significant loss, or gain of tire pressure, the tire pressure monitor
indicator icon is illuminated on the IPC and if equipped, a check tire pressure type message is displayed on the
DIC. Both the indicator icon and DIC message can be cleared by adjusting the tire pressures to the
recommended kPa/psi and driving the vehicle above 40 km/h (25 mph) for at least 2 minutes.
The LGM has the ability to detect malfunctions within the TPM system. In the event a DTC is set, the tire
pressure monitor indicator icon on the IPC will flash for 1 minute and then remain illuminated after the ignition
is turned ON and the IPC bulb check has been completed. Any malfunction detected will cause the DIC to
display a service tire monitor system type message.

 

[vipergg]

TPMS is a separate system. If your vehicle is not equipped with the system and TPMS sensors in the tires, you will not be able to monitor tire pressure via the DIC. I believe the TPMS system was introduced in 2006 on our platforms. Open the glove box and look at your build data plate. If you have the TPMS system, the RPO code will be UJ6.

I have the TPMS and even with the OBDII adapter, I cannot see tire pressure, only with the DIC. Without the DIC, all you would see on the dash is the TPMS light come on warning you that one or more tires have 25% lower air pressure than what is recommended.

However, there are after market systems that you can purchase. You will get (4) tire pressure sensors and a stand alone unit that can monitor the pressure wirelessly. I have seen them for as cheap as $100 and up to $300. Some of the aftermarket systems use actual TPMS sensors and others have sensors that install in place of the valve caps.

TPMS can be a PITA sometimes, but is a valuable system to have. It has saved my a$$ twice while on long road trips. Gives you enough warning to find a safe place to pull over.

PIA is correct . I always check the pressures and set all of them to 35 PSI yet for no reason every once in awhile the stupid light will come on and not once has there ever been an issue . The system in these seem to be prone to radio type interference . I see this will usually happen when the kids are in the car and are on their ipods and they have left the wifi on . Somehow we all survived without his expensive to repair option in our years of driving .