how does the ASC system work?

[DougZ]

What does this system do? Does it lock the diff when one wheel slips??

[2ndBimmer]

I believe that ASC uses a combination of engine retardation and brakes to stop slippage. At speed it will only cut back the engine power (by firing non optimally) but slower it will actually pull a mini-ABS thing to slow down the spinning wheel.

[BlackM42]

I believe ASC primarily operates through the use of a secondary throttle body just before (after?) the primary one. AFAIK, there is a solenoid that operates a butterfly valve, effectively cutting airflow to the engine when wheelspin is detected.
I've heard that removing the TB altogether can give quite an increase in throttle response, as the opening in the ASC throttle body is substantially smaller than the primary one. (don't quote me on any of this, my car doesn't even have ASC)

don't know much about the brake activity...

Fraser

[J!m]

The second throttle is correct, and it's before the 'gas pedal' throttle.

I don't believe the brakes are in any way connected to the ASC. That is DSC (Dynamic Stability Contorl) which applies brakes as needed to prevent spinning out on a corner. Not available in out ti's.

When I had the old motor in place, I activated the ASC plenty of times, and the anti-lock brake servo (or brakes as far as I could detect) were not activated. It just sat there. I also saw no connection from the servo to the traction control module while studying witing diagrams (and battling insanity doing so...) but, the connection could easily be made within the ECU...