I saw this in the owners manual and wondered how could the VDC know to detect this and reduce engine power?

"If the vehicle is stuck in mud or snow, the VDC system reduces the engine output to reduce wheel spin. The engine speed will be reduced even if the accelerator is depressed to the floor. If maximum engine power is needed to free a stuck vehicle, turn the VDC system off."

 

it probably relies on the wheel speed sensors, and if it sees a mis-match in one wheel spinning faster than the others then it kicks down the power...at least, that's how the simple traction control system worked in my 97 Pontiac Grand Am

 

^ What Amerikaner said^ The computer detects a loss of traction to of one (or both for that matter) of the front wheels relative to the other which has more traction. It's almost always one wheel that breaks traction before the other and the VDC attempts to reduce power to help the driver bring the car under control.

 

You guys are right, this happened to me when I was hit in rear passenger direct hit on the rim. First thing I noticed was that light come on

 

That's crazy. So has anyone found a way to disable this with out pushing the VDC off every time I turn the car on.

 

what do you mean? If you're referring to it (the light) coming on when you start the car up, that's normal man.

And if you just want to drive around all the time with it off, you have a button that turns it off. But yes, you're gonna have to push it each time you stat the car if you want it to remain off.

 

Instead of starting a new thread, just curious and I know this might be a stupid question do people drive with Vdc in the on or off position? Obviously if its a crappy day I'd leave it on, I've never turned it off, just curious if it changes performance at all in normal driving conditions

 

Witchcraft.

 

Don't even know what that means, I guess I had a stupid question, but that was an even more idiotic answer

 

The only time I would ever want the VDC (Vehicle Directional Control) off would be if I was stuck in mud or snow or trying to do some fancy off-road didos.

I would never drive on a public highway with the VDC off. I drove without any type of Electronic Stability Control system from the late 1940s until around the year 2000, and The improvement VDC offers in controlling the vehicle in an emergency situation is remarkable.

As most drivers understand, with the weight of vehicles these days, and the width of tires (When I was young, an 84 profile tire was considered 'wide'), power steering is absolutely necessary. But power steering, even on the most modern vehicles, is not instantaneous. I have no trouble turning the wheel lock-to-lock in one or two seconds, but there have been times in my long driving career when I needed to go lock-to-lock in a fourth of a second, and power steering systems will not let us do that.

But our VCD system uses reduced engine power and controlled braking on each wheel individually to accomplish far more than instantaneous steering could ever attain. Professional drivers have praised Electronic Stability Control systems, and find the same benefits that I do.

It isn't so much that computers can think faster than drivers (although they definitely can), but that a computer system such as VDC has more and better options than we drivers do of bringing any vehicle under control in an emergency.

I have already lived a long and full life, but would like to hang on a little longer. VDC helps me (and drivers of all ages) do that.

 

Great explanation, and now I totally understand the purpose, thanks lightonthehill

 

I thought VDC stood for Vehicle Dynamic Control? Don't mind me though, just nitpicking.
I always enjoy reading your posts though. Always informative and packs a lot of experience.

 

You are probably correct. This is covered in the Owner's Manual, but I am too lazy to turn off our home security stuff, disarm the booby traps and amble out into the garage and get the manual and check. It seems every auto manufacturer insists on having a unique name for their system, even though they are all essentially ESC (Electronic Stability Control) systems.