I recently switched over to my track tires (with no TPMS) only to find that tire pressure did not change on my screen. ODD. Part way there (40 minutes later) I get a signal showing 32 rear left and 1 psi rear right. At the track I am no longer able to enter competitive driving mode. I have ran this set up 15+ times at the track with never an issue. Also unless I disable traction control my car will display "active handling" after a minute or so of driving and I can feel the car start to drag. I can only switch between traction off and active systems on.

So now a month or so later the car does the same thing every single time. But often it will show 32 psi both rear tires (still no sensors). It will randomly change between 32 psi, 1psi and XX.

This is on a 2007 Z51 package.

Putting the stock tires back on made no difference.

I've scanned the car at my shop however I see no obvious sensors out.

Any help would be great.

 

Hmmmm.....I don't find it odd at all that your car is doing that - it was designed to work like that.

What is odd that it didn't do that in the past.

Oh well, at least your car is acting normal now.

I run sensors in my '06 Z06 to avoid AH problems.

You say you "scanned the car". What did you scan it with - a Tech 2, an OBD2 scanner, or a TPMS tool???

The sensors being inop or not installed won't generally throw any DTC's. Problems with the TPMS may.

If you have a fairly high-end TPMS tool you can do some diagnostics to see if your sensors are okay or not. If you have a GM J-46079 TPMS tool it will simulate a set of sensors so you can diagnose problems withe the TPMS computer in the car.

However, it sounds to me like your car is acting just like it is supposed to act when you run with no sensors.

You say "track", and you keep mentioning the rear tire pressures.

Are you talking about a drag strip or a roadrace course?

Are you swapping just the rear tires to DR's for the drag strip, or are swapping all four for running a road course?

Bob

 

I only swap out the rear tires for 1/4 mile.

I do not see why it would display tire pressure with no sensors installed. On the way home tonight it displayed 31 and 1 Psi with no sensors installed. Normally it displays xx on both sides if the sensors are missing and or not functioning. I checked the sensors in the tires and they are all functioning properly.

Thank you for the response Bob.

 

I don't know why you're getting pressure readings with 2 sensors up front and no sensors in the rear.

Like you say you previously experienced, you should be getting a DIC reading of xx psi for both rear pressures.

When you swap on a pair of DR's with no sensors and leave your street tires wih sensors up front, the car will receive signals from the front sensors as soon as you start driving. It knows the TPMS is working because it got signals from two sensors, so it knows almost immediately that something is wrong with the other two sensors and will inhibit Comp mode.

However, if you don't have any sensors in any of the 4 wheels, when you start driving and the car gets no sensor signals, it thinks the problem is probably the TPMS (nobody would drive with no sensors, right!).

When it gets no signals, it will go for a period of time before it gives the "Service Tire Monitor" (that means it thinks there is a TPMS problem) message comes up. Before that message displays in the DIC you will be able to go into Comp mode or turn AH off completely.

However, once you get that message you won't be able to go into Comp or turn AH off completely, and if AH were off or in Comp, AH would come back full on.

What's the period of time???

Well.....it depends on your model year. The 2005 through about the 2007 is 60 minutes. I think it was 2008 (may have been 2007) where they reduced the time to 30 minutes. With the 2009 model year it went down to 20 minutes.

That time period is one ignition cycle, i.e., you can run for that time and you'll be able to turn AH full off or Comp for that time period.

After that period of time you can shut down, restart, clear any "Service Tire Monitor" message or any other if still present, and you should have another 60/30/20 minutes where you can do what you want with the AH.

So.....what I would do if I were a drag racer is - I would have a pair of skinnies with no sensors, or at least another pair of street tires with no sensors, so that I would have no sensors at all. That way I'd have a period of time from starting the car before I had problems. At the drag strip I think you never have to exceed even 20 minutes of engine running time from leaving the pits to completing a run.

If you're running road course sessions, the 2005-2006 has an hour, so that should cover most all track day sessions. If you have a newer car you'll only have 20-30 minutes from when you start the engine until you encounter problems when running with no sensors.

If you have another set of street wheels to put on the front, try running with no sensors at all and see if you have a period of time before encountering the problem.

Bob

 

I have a set of fronts I just don't ever swap them. My biggest problem is even with my stock wheels on with all 4 sensors verified working properly I still get these same readings. What is odd to me is it happened this last time I changed tires. Now it seems like its stuck in this loop.

 

This is a common problem with lots of pain spent by members trying to find a solution. The TPMS system on these cars is finicky at best. My car, nearly every time I drive it, gives me a "tire flat" message. Eventually it comes to it's senses but it's quite annoying.

I have created a box that eliminates TPMS issues altogether (but sill lights the warning light and gives accurate readings), I think I sense a market to sell it for frustrated C6 owners

 

Whats this fix you have?