Here is my question. How do you disable the AH/TC/ABS enough to do a dyno run? Yesterday we were working on the baseline testing of our new C5 race/development car. In addition to some lapping at Miller Motorsports Park, we also stuck the car on our Dyna Pack to get some baseline engine numbers for future reference.

We would let the clutch out to start to do a pull, and the rear brakes would start to pulse, then pulse more and after a couple of seconds basically shut the car down. No problem, makes sense, the front wheels are stationary, rears are spinning. We turn off AH, same BS.

Now this is a Dyna Pack pod dyno, so the rear wheels are off and we can watch the calipers pulsing as the brakes are applied. I figure, next step, pull the wheel speed sensors for the rear. Same BS except now I have a service ABS and AH warning in the DIC.

I tried the following things:
1. disconnect wheel speed sensors (rear only)
2. pull ABS and TC fuses in underhood module
3. pull main connector from ABS unit (I can't believe that didn't work:laughing: )
4. disconnect the single wire going to the ABS pump motor.
5. disconnect the speed sensors from the transmission (although maybe not the correct one because the IP still showed vehicle speed)
6. every possible combination of the above items

Finally I had to resort to the brute force method. I took the damn rear calipers off the rotors. Even that threatened to not work because the AH started to pull power from the engine by closing the throttle. I played around with the AH button and that finally went away.

Again, what is the correct way to disable that crap for a dyno run? I'll post some of my results after I look over the data a little more.

ciao,
Aaron

 

All you have to do is turn the traction control off on the center console. The button that has a picture of a vette. this will diable the traction control. You will get the light for the abs and traction control, but it will go off as soon as you drive it on the street.

If that doesn't solve the problem, you have some issues

 

What year is your car? On mine, first press of the AH/TC button turns off BOTH AH and TC .... holding button for 5 seconds gives COMPETITIVE mode ... which you DO NOT want for a dyno run as AH will still be on.

With TC and AH off you'll still get codes from the EBCM because it thinks there is something wrong with the rear wheel speed sensors showing X MPH and the fronts showing 0, but after you're done clear the codes and all should be fine.

 

Issues, issues, issues. Yeah, the first thing we did was turn the TC off with the center console button. That didn't change anything. So we shut the car off, restarted it (like Windows) and turned TC off. Still the same deal.

That is when we started getting creative. Seems like this is unusual. The car is a '99. I can't even imagine the problems we'd have in our C6. I can't even get the TC/AH to stay off while I'm on the track. Hold the button for 10 seconds, do a little dance, turn the wheel left mash the throttle and hope the AH stays off. But I digress.

-Aaron

 

Hmmm .. if you take the car on the street and turn off TC, can you then do a burn out uninterrupted by TC? My car will definately respond to my turning off TC. I can light the tires as much as I want once it is OFF. If on, I can "chirp" the tires, but anything more aggressive will cause TC to step in and limit wheel spin.

Same with AH. I've had my car at Laguna Seca, Willow Springs, and Sears Point (Infinion) ... and if I have AH off I can (and have) spun the car !!

Steve

 

I have never heard of any dyno troubles with C5's, as long as traction control and AH are off. I had mine on a dyno a while back and the same issue you are describing happened. It worried me for a second since I just installed h/c myself and was getting it tuned -- thinking something broke. The tech laughed, shut off the traction control, and everything was fine.