Anybody know if and why simply coasting down a hill and then getting the car in learn mode wouldn’t reset the TPMS? Has anybody tried this?

and as long as I'm talking about it, doesn't putting the car in competition mode allow you to swap wheels without resetting TPMS (which would eventually put the car in limp mode)? IOW, competition mode disables the TPMS?

 

why WOULD it work exactly?

 

How do you get the car in LEARN mode? I don't think that's mentioned in my owner's manual.

 

turn ignition to ACC
press FOB lock and unlock buttons at same time
horn should beep indicating it is in learn mode

do not do this unless you know what you are doing!

 

sensors do not send info unless tire is rotating, the whole purpose of tool is to force the sensors to send info, so if car is moving, sensor is sending info

the thing I am wondering is, to reset do the sensors have to send info in a particular order for the reset to work correctly? I am thinking this method would work, but the ECM may not have the tires in the correct position to what they are on the car since in all likelyhood the first sensor to send it's info would not be the correct one (the left front followed by the right front, right rear, then left rear)

if so, then you might have to do it 24 times to get it in the right order (laws of chance say the order would occur 1 out of 24 times)

 

i see what you are saying now. Yes by the way, there is a definite order. The reset tool prompts which tire to start at and which way to go around the car.

 

Check out the videos in this thread (Courtesy of CF Member "BEZ06"):

http://forums.corvetteforum.com/show....php?t=1495228

 

After my wide body conversion, I replaced all four wheels and tires and put on brand new GM sensors. I never reset anything! But my readings are 30lbs in all four tires. I checked them with a gauge and that's what's in them. Am I missing something/ Or did mine reset on their own??? I know the body shop just put the wheels on that I brought them. The tire dealer told me they would restet on their own once mounted and driven.

 

BEZ06 will set us all straight when he gets to this thread. I think your TPMS are sending the correct pressure reading but without doing the learn thing it doesn't know which sensor is in which position on the vehicle. So, if you loose pressure in say the RF it might show in the DIC that it is the LR or some other position because it doesn't know which one is in which wheel. If your pressure changes in any tire it may show the wrong location. That's why you "relearn".

 

BEZ06 is the true TPS / TPMS tool expert but I'll give it a shot...each individual sensor registers a unique code number with the computer so the computer recognizes that particular sensor at its particular location. There's no way the sensor can be 'excited' to transmit the individual sensor code number to register it with the computer by simply by rolling the tire.

I change from my street tires to my track tires are the track each month. I use a Schrader-Bridgeport TPMS tool. On one occasion I was having trouble getting the final sensor to register (my LR wheel). My group was already on track so I said the hell with it and went out anyway. I got an immediate DIC warning regarding the tire pressure sensor. There was no way the car would go into comp mode. The sensor did not reset itself because the tire was rolling. The end result was TC and AH were coming on so often it was totally messing me up...it was virtually impossible to drive safely at speed. I exited the track after one lap, I went through the registration procedure again with my TPMS tool and everything set just fine.

Hopefully BEZ06 will jump-in...he's the true expert on the subject.

 

You haven't driven far enough it takes like 26 miles for the sensors to cause the Car
to come up with the flashing tire on your speedo, Then the Dic will says service tire montior.Then you'll need a reset. Happens every time I change wheels.Right now your still showing your old tires pressure of 30 pounds. They don't reset on there own the tire dealer is full of it.

 

of course it didn't reset, you did not put the car in relearn mode

also, since the sensors will not send a signal if they are not rotating you should have put your car in competition mode before you set out, than everything would have been OK

could someone who knows what they are talking about substantiate? in competitive mode you can install wheels wheels without resetting TPMS, and car will run fine?

 

Velly Intellesting!!!!

First of all - the TPMS computer will not recognize any sensors that have not been logged into its memory by doing a relearn procedure. You cannot just put new sensors in the wheels (or a different set of wheels with different sensors) and expect the car to automatically learn them - won't happen!!!

Second - You must do the relearn procedure in the order LF, RF, RR, LR. Well.....you don't have to do it in that order, but when in the learn mode the first sensor triggered will be logged into the TPMS memory as the LF, the second as the RF, etc., so if you do it in a different order your DIC display will not correspond to the correct wheel. That's the same reason you need to do a relearn if you rotate the tires on your Tahoe or Escalade - the sensors will still work and the TPMS will recognize them, but it doesn't know they're now on different corners of the car.


When the car is parked for more than 15 minutes the sensors go into the sleep mode to save their internal batteries and only transmit once per hour (60 minutes). When you start driving faster than 20 mph the sensors wake up and start transmitting once per minute (or sooner if they detect a certain change in pressure).

Take a look at the video below using an official GM sensor reset/TPMS tool - a Kent-Moore J-46079. This tool is really nice because it has a screen and displays some good info.

In the video below pay attention to the bottom of the screen - after I trigger a sensor with a transmission from the tool it displays "Learn Mode" toward the bottom of the screen.




There are 3 buttons on the tool. When you power it up there are functions displayed on the screen above each button. The first button is the "Activate" button, the second is the "Scan" button, and the third is the "Simulate" button.

The Simulate button is only used to test the TPMS computer in the car.

The Activate button is the button I always use to trigger a sensor that requires a radio frequency wave to trigger them, such as our C6 sensors. When Activate is pushed the tool transmits a 125 kHz radio frequency transmission that will trigger or excite the sensor and force it to transmit its data to the radio receiver in the TPMS computer of the car.

I seldom use the Scan button. The only time I've used it is to do diagnostics on C5 sensors that are triggered by a magnet instead of the 125 kHz radio frequency. You push the Scan button and the tool does not transmit, but it only "listens" for a sensor transmission. For the C5 sensors, I push Scan, put a magnet over the valve stem (which forces the sensor to transmit), and the tool picks up the transmission and displays the exact same info you see on the screen in the above video - including "Learn Mode" on the bottom of the screen.


Now for the interesting part!

I had never done this before, but I went out into the garage, powered up the tool, pushed the Scan button and waited. And nothing happened!! The tool powers down after about a minute with no buttons being pushed. The car had been parked since yesterday, so the sensors in my tires should be transmitting once per hour, and I guess if I kept turning on the tool I might have gotten a transmission from one of the sensors after a while.

I went out driving around my neighborhood for several minutes at a speed faster than 20 mph. When I shut down the car I turned on the tool, pushed the Scan button, and waited. And after about 20 seconds I got a display on the screen!!! I was standing outside the car about 2 feet from the driver's door. I pushed the Scan button again and after about 30 seconds got another display with a different sensor ID#. I tried it again and within about 15 seconds got another display with a different ID#.

So.....the sensors were transmitting once per minute and I was getting random sensor ID#'s of the 4 sensors in my C6. I don't know which #'s are on which corner of the car, but the TPMS computer does, and that's how it knows which pressure to display for each wheel position.

The interesting thing was something I had never seen (because I hadn't ever tried this before), but on the bottom of the screen it said "Drive Mode".

I'm not sure, but what it seems to me is that the sensor sends out a different data stream with different digitized data depending on whether it's being triggered (forced by a tool) to transmit (in which case the tool and the TPMS computer knows the sensor is transmitting in the "Learn Mode" and the tool displays that on the screen), or whether it's just transmitting while driving down the road (and the tool and the TPMS computer pick up that different info in the transmission and they know it's the "Drive Mode" and that's what the tool displays on its screen).

I also put the car into the learn mode and pushed the Scan button on the tool. After about 20 seconds it picked up a transmission from one of the sensors and displayed "Drive Mode" on the screen, but the horn never honked as it would have if the sensor would have been transmitting in the Learn Mode.

So......I'm not sure how you'd put the car in the Learn Mode while going down a hill (engine shut down, push bottom of ignition button for ACC mode, push and hold lock and unlock buttons until the horn honks). I think you'd be asking for trouble trying to do all that while steering with no power steering. You wouldn't need to do all that anyway - the sensors keep transmitting once per minute until the car has been still for 15 minutes. Just go driving for a few minutes and try it when you park the car - like I did.

Butt......It won't work anyway, because the sensors would be randomly transmitting once every minute in the Drive Mode, not the Learn Mode, as is required to do the relearn procedure and log the sensor ID#'s into the TPMS memory.

Bottom line - You need a tool that will transmit the radio frequency to trigger the sensor to do a relearn procedure.

Bob

 

thanks for the very enlightening info Bob

does anybody know the answer to my question about switching wheels , not resetting TPMS, and running in competitive mode? it is my understanding in competitive mode the car will not go into limp mode, if not in competitive, it will go into limp mode

 

learned something new...about to change wheels...

 

You're sorta right! The car won't go into limp mode in Comp mode because if you're in Comp mode (or AH completely off) and the TPMS does not get signals from the sensors, the car will automatically turn AH full on - so you won't be in Comp mode anymore!!!

There are actually a couple different ways to get the so-called "limp mode". In my experience the limp mode is just a message that tells you to limit speed to 55, but you can go as fast as you want. However, other forum members have reported that if you drive aggressively when the limp mode is active that the car will pull power to limit speed (it may have to do with the yaw rate sensors and accelerometers exceeding certain limits that will tell the PCM to pull power).

One way to get into the limp mode is for a sensor to go bad and stop transmitting. The car will know this almost immediately after you start driving faster than 20 mph. When 3 sensors start transmitting, the TPMS is expecting the 4th to check in. When it doesn't, you'll get a message to "Limit Speed to 55" very soon after you start driving . When this message comes on you will not be able to go into Comp mode or turn off AH completely. If you had AH off or were in Comp mode, the AH would automatically turn full on.

The same thing will happen with 2 sensors inop - such as if you put DR's on the rear with no sensors in them but have your regular wheels with sensors on the front. Butt.....you can still turn off TC, and when drag racing you don't want to turn off AH anyway. But, as mentioned above, some owners have reported getting reduced engine power under hard acceleration while in the limp mode.

Another situation is if you have NO sensors (or put in new sensors or a different set of wheels with sensors that are not registered with the TPMS). The TPMS doesn't get transmissions from any of the 4 sensors and this situation takes "approximately one hour" according to the owner's manual before you'll start getting messages. What this means is that if you have no sensors, or sensors that are not registered, the TPMS will tolerate not receiving any sensor transmissions at all for one hour before it just can't stand it any more and then it gives you a message "Service Tire Monitor", probably followed by the limp mode message "Limit Speed to 55". This "approximately one hour" is without shutting down the engine. If you do get this message and the AH automatically comes back on, you can shut down the car, restart, clear messages, and you should be able to go into Comp mode or turn AH off for another hour before getting the messages again.

So.....the car is trying to protect you when the tires go flat. If one sensor transmits, the car knows it should be hearing from the others, and if it doesn't it gives you an alert almost immediately. If there are NO sensors, it takes an hour of steady driving without shutting down the engine before it will give you an alert.

In either case above (or if you actually have a flat tire), when you get an alert of a sensor or pressure problem, you will not be able to go into Comp mode or turn off AH, and if you were in one of those modes AH will automatically come back on all the way.

I like the sensors, the TPMS, and the DIC display of pressures and sensor or pressure problems. I have sensors in all my wheels, and I have a tool to register the new sensors every time I swap to a new set of wheels/tires/sensors - and it only takes about a minute to do it.

There are some cheaper sensor reset/TPMS tools available, but if you have any interest in one of those more expensive GM K-M J-46079 tools with a screen, PM me.

Bob

 

so, talking to one of the RF Uuber geeks at work revealed that he has implemented such a system in a different application, has a board already designed and built that he claims could be partially populated and do the trick, cost about 5 bucks!

 

What does this post mean??????

 

I think what he means is that an electronics engineer he works with has developed a Radio Frequency transmitter that could work with to trigger our C6 sensors.

I don't know 'bout 5 bucks, but there's no reason something like this could not be built for $20 or $30.

cadguymark, tell your RF geek buddy that what is required to trigger the C6 sensor is a 5 to 7 second continuous wave 125 kHz transmission.

Let us know what he comes up with!!!

Bob

 

he already has a pcb assembly for an application he is working on that has it as part of his design, he showed me what I would need to populate on the board, the board has an antenna on board as etch, the cost estimate was his but I'm sure if you ordered just the parts needed from Digikey it probably would be 20 bucks or more

the first step is to get a spare a board, solder the neccessary parts to the board and give it a try

while looking around the internet electronic project pages for perhaps someone who has built one I found a third brake light pulsar which is based on a couple 555 timers , a tip125, an SCR and a handful of chip R & C's which literally could be built by sweeping the floor in the electronics lab, might have to give that a try too

http://www.electronics-lab.com/proje...002/index.html

here is a link some people may find interesting, Freescale has a chipset solution for a TPMS system

http://www.freescale.com/webapp/sps/...02Wcbf123FQ1Dg