Tracking a C6-no pressure sensors
 

so I'm all set to run my 05' at the track this weekend, and I come across a thread in the C6 Tech section. They say that if I run my track wheel (with no pressure sensors), the car will think I have a flat an either shut the car down, OR make extreme efforts to restrict my speed.

According to that thread also, if the TC is shut off, it will come back on.

The shop manual for 05 only mentions the warning lights, but does not tell me about actual performance restrictions.

I have LS2 edit on the way, and hopefully I can tune out any Torque Management (or disable the warning all together).

Anybody here (people I trust for track stuff) have any definitive info.

Dave

make sure to disable the on star too!

David the early '05s did not have that problem. Not sure what VIN was the change.

Try putting some track wheels on and drive down the road and back.

Dave, I'm not one of your "trusted authorities" but here is what I know. Another autocrosser in our club bought a new C6 earlier in the year and has been autocrossing it without problems. He recently bought a second set of wheels (without pressure sensors)for a second set of aotucross tires. He was then unable to select"Competitive Driving" mode. The dash read out noted a flat tire with a caution to limit speed to 55mph. The computer did indeed limit his speed and handling characteristics. After consulting with our sponsor dealer they called GM Tech assistance for advice. GM said the computer requires input from all 4 pressure sensors in order to make "Competitive Driving" mode available. Without the 4 satisfactory pressure inputs the computer limits vehicle speed and enters a "safe" operating program until the (unsafe tire pressure) problem is repaired. GM also said there was no way to trick the system. Their suggestion was for him to install the 4 missing pressure sensors.
Tis all I know about this. I Hope it's useful.

Dale
North Florida Corvette Association

Dave we had a brand new C6 Z06 come to the track this weekend and he broke the value stem and in replacing it the sensor was not replaced properly and the car believed it had a flat tire all the time and would compensate for that. He thought about the problem all night and duct taped the sensor to the rim and the car ran fine on Sunday and turned in some very impressive times.

David,
Yes this is very BIG problem with C6 and C6 ZO6. Haven't crossed this street yet , but I have been working on it. Myself and a certain gentleman who builds race wheels are thinking about putting all four sensors in a can that is sealed and pressurizing the can , then toss can in vehicle.
Or you could just install these sensors in track wheels, albeit expensive and needed "special" training equipment for new sensors.
I'm not looking forward to this crap on my new Z06 when I decide to buy.

the whole point of my running the track wheels was to protect my stock wheels and tires. Even dismantling to get to the sensors risks damaging the wheels.

My 05' is a very early car, and I'll hope for the best. Tires just came in today, so I'll try and get them on the car tomorrow.

Dave

Wheel needs to be machined for the sensor ... not just a drop in issue.

I guess that would depend on if his track wheels were stock wheels or
not. If I remember correctly , you've been through this. What did you do ???? Is putting all of the sensors in a pressurized box inside the vehicle and viable option ?????

We had two C6's at Roebling last weekend, mine and a friend of mine. On the trip over one of his sensors quit on him. He was not able to enter Comp mode with the failed sensor. His vin was in the 1300's.

guess my C5 just went up in value ;)

Frankly, they all seem to behave differently.

Mine is a December build. If I drive 50 or so miles and the car can't see the pressure sensors it will turn on TC and keep your speed down. I can, however, still turn TC/AH off. Rex used to be able to do the same with his early C6 but he can't with his new one.

An additional note, I bring the stock rims/tires with me and the car is never the wiser. I don;t know the specifics on how/when it checks when the wheels with the sensors aren't in motion but I can say for sure that the car "sees" them.

Another interesting tidbit, with C5 Z06 rears and 285/35/18 Hoosier S04s and the stock C6 rims in front with 245/35/18 Hoosiers on it the car didn't balk at this setup if I left TC/AH on. With C5 Z06 rims and 305/30/18 GAC slicks all the way around the car almost immediately gets upset and turns on the TC. Strange beast.

I'm bringing a square setup, 280 slicks all around. That's the best set of cheapos I could come up with quickly. I likely won't bring the stockers, as I'll be packed to the brim with 2 cars, a mule (kawasaki) and tools. If it works, I'll drive it, if not, I'll park it. Mine is an early car (Aug 04 production), so I've got my fingers crossed.

btw, LS2 edit can't write it out, as it is a BCM system, not PCM. However, I'm hoping maybe I can tweek the torque management if push comes to shove.

I wonder what would happen if I disconnect a wheel speed sensor? On a C5, this would shut down the entire TC and ABS system. I hate to lose ABS, but that's better than being artificially held back.

Wow-August 04 is *early*. I think you should be good to go (I'm guessing you drive with TC/AH off-I don't think I even tried comp mode)

the guy bought the car in September, so I'm guess August. Anyway, the car looks better than new, and I saved a good amount of money. I also liked the 05' as I can tune the engine myself, and their are lots of parts coming online. Supposedly, the 06' models have even more complex computer systems.

Honestly, so far, I do hate the electric door crap, and havn't figured out the memory seats/radio yet!

My way of dealing with this would be to buy an extra set of sensors and have them band mounted within the track wheels. You'll have to do the relearn each time you swap the wheels, but that won't take long once you've done it a few times. Its unfortunate that GM's software does what it does. Sometimes I think GM is trying to be "too smart".

- Mark

They are trying to protect themselves from sleazy product liability lawyers in any way they can.

Unfortunately you can't train the C6 sensors with a magnet like you could with a C5, you have to have the RF tool (as far as I know)

From what I'm reading in this thread, without the sensors the car won't go into Competition Mode. Can you still turn everything (AH/TC) off without the sensors?

As was mentioned above, just carrying sensors would not do it. They would have to be pressurized or the computer would still report flat tires. Somehow the computer needs to be able to shut this feature off. I see a lot of unhappy campers with this problem.

This is one of the reasons why I have not bought a C6, yet. I researched this issue and no good solutions. I wanted to use CCW wheels w/o sensors. I did not want to use stock wheels.

I liked Rex's idea of putting four new sensors in a capped pvc pipe with an air stem to pressurize. Then just throw it in the trunk.

That sure seems like the easiest way to skin the cat.

Any good used Miltiary ammo can works--as long as its still air/water tight.

don't the wheels have to spin to activate? I guess you could "shake" the can??!!

Or maybe it's the car that activates in the C6's

David, I can't speak for the C6, but I left my stock 2002 wheels with the sensors mounted in the garage for a while, and everytime I would pull in and just get close to them, the car would pick them up. Even now that they are on the other side of my apartment, at least 20 meters away for the driveway, the car still picks up one or 2 of the occasionally.

Wow... what an annoying issue to deal with.

On my Mom's '99 with sensors it doesn't register a pressure on the DIC until you hit 15 mph I believe. Not sure what you'd need to do on the C6.

Funny that they put so much emphasis on tracing the cars yet do this to you w/ no good way to override it.

On later model C5's they changed that. The sensors were active even when sitting still and didn't require movement.

I don't know what they have done on the C6's.

The tire sensor is an OBD III requirement and as a result the tire sensor cannot be progrommed out since it is in the firmware. All C6 Z06's and 06+ will have it. Some early 05's did not have this update when made. If you pull a fuse, etc it will go into disable mode, from what we were told. The sensors are the same or similar as on the Yukon/Tahoe vehicles with sensors. I am not sure if they have aluminum stems or not, but if they are steel, you might want to swap them out.

Just thinking out loud:

I'm not sure if anyone has cracked a sensor open yet, but the normal operation is the pressure sensor to correspond to either a resistance or voltage. If someone has the inclination, you could probably replace the actual pressure sensor with one to trick it into outputting the "ok" signal to the car.

<edit> after looking over datasheets for some of the motorola sensors, it looks like most are integrated solutions (ICs), so it would be quite a bit more difficult than discrete components. still, an aftermarket should be able to come up with something.

Yes the sensors will have a resistance or a voltage that corresponds to psi, then that is transmitted at a frequency to a receiver to the cars computer.

So the solution is to dream up a "black box" that emulates the same resistance/voltage and transmits to the computers receiver the corresponding required tire pressure. This is easy doing for an I&C nerd technician or engineer. Anyways I agree, an elegant solution should be on the horizon I'm sure.

Interesting comments about tires not on the car but nearby affecting the car that already has four tires with sensors. What happens to the computer when it has more than four sensors sending information? I would have thought they would be adjustable to a unique code. Kinda like a garage door transmitter. Oh well. GM has to aggravate us to no end. :D

So if some one designed a SUPER BLACK box that had a rotating frequency to the GM / Corvette TPS and the put that SUper Black Box on the pit wall to signel each car that when by they had a flat. Could that happen too??

I don't need a computer to tell me when I have a flat tire. Too bad 99.9% of drivers on the road are incompetent, rude, and dangerous.

It still bugs me that every car I buy seems to have a good 1/3rd of its value in safety crap(8 airbags etc). Don't get me wrong, I'm all for seat belts and even 2 airbags, but you reach a point where driving is simply dangerous, and we need to get over it.

btw, I won't be wearing my head restraint this weekend (may not even wear my nomex unless I get cold)

Tom,

Anything is possible. I think we need to sanitize this thread for national security reasons. We don't want to give the terrorists any more ideas to mess with us. No "super black boxes" for the terrorists. :D :flag:

why pass on the restraint ?? unless your running factory 3 points...

because it is a PITA to get in/out of the car, and you can't turn your head. Besides, I plan on crashing backwards :)

Dave,

Do you have the HANS?

Don't worry, the computer will keep you in safe mode, you won't even need seat belts :jester

I agree that it was a pain when I first started using my Hans. Once I got used to it it was easy to exit the car with it on. After seeing a Mustang burn to the ground @ Beaverun this year I decided to start getting out of the car with it on instead of taking it off while I was in the car. I have been using mine this whole year and don't think I will ever drive without it as I feel naked without it on when racing.

I agree that it does limit side to side head movement but I really only move my head that much while I am in the pits anyway.

The worst peice of safety equipment is sitting in the trailer when you are on the track.

I was so worried about this that I purchased a set of wheels and brand new sensors and a $200.00 tool to program them. I put the track wheels (C5 Z06 18 x 10.5's) on the car before I put it on the trailer at home. I brought my street wheels and tires incase I had a problem since I had never been to the track with the C6 and because of worries about running 18 x 10.5 all around. When I got to the track and unloaded I forgot to program the sensors to the car. The next morning, first session I turned off T/C and A/H and did my twenty minutes. I did the same thing for two days and eight sessions of twenty to thirty minutes. I never got a message about tire pressure. Sat. night we installed the street wheels and tires and drove to Waco to see the Baylor Bears play (my son went there). Back to Ft. Worth Sat. night after the game and race rubber installed again Sun. morning. When I was installing my street rubber back on the car to drive it on the trailer I remembered that I had never programed the sensors to the car. I don't know if it worked because my street wheels were sitting ten feet from where I pulled in or what. I even tried comp. mode second to last session on Sun. and it worked perfect! I still think it's cheatin and will keep you from learning as fast to depend on a computer to save your rear but to each his on. My car is a May build. I wish I knew if I really needed the sensors and the tool but since I have already bought them I will keep them just incase. I am doing another track event next month at MRS and I will report back. I may even move my street rubber way away from the car to see if that is what is making it work.


Jerry

Memory seats will only move when parking brake is on.

I have the 3R, but used the Hutchins prior. I used them for racing, but not for DE or open tests.