Gwozdz

A few days ago, my '04 coupe with MN6 started having its active handling being triggered whenever I make a 90 degree left or right hand turn at slow speeds. The Active Handling message shows up on the DIC, the ABS fires and the car almost comes to a halt. I have not noticed any problems when I am on the interstate nor when I turn active handling off. The problem seems to be very reproducible. No TCS codes are being stored.

I just spent the last two hours reading about active handling problems and could not find my problem discussed. I did find this thread

https://www.corvetteforum.com/forums...g-problem.html

to be interesting as a general approach to the problem but I am wondering if anyone can point me in a more specific path since my problem is quite specific and the daytime temps are in the 30's so working on the car is somewhat of a chore. Tomorrow, I will go out and see if any codes show up before shutting the engine off. BTW, I did personally replace the steering wheel position sensor a year ago but I did so as a result of a code.

This forum has saved me on several occasions in the past with the answer already posted but this time I may be stymied. Any thoughts would be greatly appreciated.

65GGvert

I'm curious as to what size tires you're running.
I'd also be thinking maybe the SWPS you changed might have an issue.

Gwozdz

Thank you both for your suggestions. I spent the day more or less chasing the problem down further. I am curious if you agree.

The tires on the front are Good Year Eagle F1 245/45/ZR17.
The tires on the rear are Michelin Pilot Sport AS 275/40/ZR18.
I have had this configuration for at least a year now. I also made sure that each tire had 30PSI this morning.

The car still behaves the same way though it did not seem to stop as violently while cold. Perhaps the brake shoes needed to warm up. I looked for codes immediately after the Active Handling message occurred and still no TCS codes.

I then took it over to my friends shop and one of the mechanics put a Snap-On computer on it and verified no codes but also found that the Steering Wheel Position Sensor would read nothing but 0 (zero). He thought that he was reading the sensor correctly but we can't be totally sure since it just did not respond except to say 0.

My hypothesis is that the sensor always says that the car is going in a perfectly straight direction and as soon as the wheel sensors disagree, the ABS is activated. The big question in my mind is whether the computer can be fooled into thinking that the car is only going straight and therefore does not record a code telling me that the sensor is bad?

It is 26F in my garage and I am not that anxious to replace the SWPS again a year later. Any other thoughts or should I place my order for a new sensor and put on my long underwear? Thank you again for the help.

martysauto

How many miles are on your car? I have seen front wheel speeds drop out to zero during low speed turns. It's usually due to the wiring going to the sensors starting to fail from flexing many times over the years and miles.
Before you start freezing your *** off and spending time and money, I suggest you find a shop that can graph you wheels speeds during a road test. If one is dropping out you will see it.

Gwozdz

Interesting! I did go for the road test but I was driving. When I asked the first mechanic what he was seeing, I did not really get a straight answer. I am not sure how familiar he was interpreting what he was seeing. The owner of the shop (my friend) is getting back from Disney World tomorrow. I will ask him to repeat the test in light of what you are saying. My friend's Snap-On computer can do the graphing since I saw it done for my '98 Mark VIII when one of it's wheel sensors failed. My friend showed me what was going on. I guess that I should have pressed harder for a straight answer but beggars can't be choosers. Mechanic #2 wasn't sure he was interpreting the SWPS correctly but at least told me he wasn't sure.

Maybe I won't freeze yet! Thanks for the help.
BTW, to answer your question, the car has about 70,000 miles on it. It spent a couple of years in Kansas, a couple of years in Texas and now a couple of years in NJ.

martysauto

It's definitely worth a look. It's quick and easy!

kabluie

The car has two or three G-meters. If your front G-meter is going honky, then that may be your problem.

I only suggest this because the owners manual talked about the G-meters in the part about the Traction Control System. I think you need to look at the whole system to be sure about what your fix is going to be.

Gwozdz

Thank you all for your comments. I had the opportunity to use a SnapOn Modis Ultra analyzer to look at my active handling system while driving. As before, the Active Handling comes on anytime I turn left or right, worse at slow speeds. Here are the screen shots for two test runs. The last screen shot of each test run shows that the Brake Pressure Sensor does not seem to be providing a signal but I get no error codes at anytime. I don't know if the sensor could still be bad or the analyzer is just not picking up the signal correctly. I also don't know if a bad Brake Pressure Sensor could explain my symptoms. It appears to me that the steering wheel position sensor seems to be working as well as the G force sensors but you all may have a better clue than do I.

Thank you again for your help and suggestions.

















TEST RUN #2

Gwozdz

Kabluie,
You were right. No codes, but I read the same info in the service manual and on a whim, went ahead and bought a used Yaw Rate Sensor (the one that sits under the radio). Fixed the problem!

If I have the opportunity, I will try to put the car back on the Snap On analyzer and take some more photos to see if the waveforms for the Yaw Rate Sensor appear differently. Perhaps I just have an overactive sensor.

For 40 bucks, I am again a happy man. Thanks so much for the help.

dharmadan

Thank you -- enjoyed reading.