This is from an article that I found that might better explain some background to the "Traction Control and ABS" system. The newer technogy you mentioned that runs through the ECM is generically called "Drive by wire", I guess this latest setup has eliminated the throttle cable as we know it. Unsure of what year they made the transition to the newer technology, someone on here might be able to chime in on that one.
"Traction control is part of a series of three braking technology developments that began appearing in vehicles in the mid-eighties. (Note: Many German vehicle manufacturers call traction control by its original German name: ASR traction control. ASR stands for "Acceleration Slip Regulation." It'* the same technology we're talking about here, but with a fancier name that most Americans have never heard of.) In chronological order, these developments are: anti-lock brakes, aka ABS (197
, traction control (1985), and stability control (1995). All three technologies come from the laboratories of Robert Bosch Company in Germany, and all address the issue of improving contact (traction) between your car'* tires and the road.
Let'* say you're at a stoplight on wet pavement. The light turns green and you press too firmly on the accelerator pedal. There is slick asphalt under your tires and the wheels begin to spin. The traction control system instantaneously kicks in, sensing that the wheels have begun to slip. Within a fraction of a second, this data is fed back to the control unit, which adjusts throttle input and applies braking force to slow the wheels (some older systems also retarded engine spark). The wheels are thus prevented from spinning and the car maintains maximum traction.
It'* really that simple. Again, think of it as ABS in reverse."
When you hit the button that says TCS, it enables or disables the accelerating portion of the system, you do not have the option of toggling the braking portion.