Traction control vs. ASR
 

I know from searching the archives that various iterations of this topic have been discussed, but I am a bit confused.
I have the original sticker for my 95S320 and it shows that it came with "electronic traction system" as standard equipment. It also shows that it came with "ASR-acceleration slip cntrl" as an ($1650) option. Can someone explain the difference? Thanks folks.

ETS was STD equiptment & that only is a "braking" control traction system. ONLY 3 wheel speed sensors, both front wheels & a differential sensor.

ASR is both a braking & accelerator control system, can apply the brakes OR back-off the throttle opening to reduce torque. This system as well as most other systems use 4 wheel speed sensors.

Thanks for the reply M.B.!
Hate to beat it to death, but I am trying to understand it. Why would you need ETS for if you have ABS or am I totally confused? Thanks again.

What I think MBDOC means by "braking" traction control system is that the system (ETS) senses slippage during acceleration in one of the wheels and applies the brake to it. This pushes the torque accross to the other wheel through the diff.

ASR adds the extra component of controling the engine power in order to bring the car back under control. You punch the gas and the car says no way buddy I am not letting you have this power so you can run us into the trees! It cuts the power and thats putting it very very simply. Basically I think ASR steps in when you try and overwhelm the ETS by applying more power.

ABS is strictly a brake control system when you are coming to a stop on slippy surfaces.

Thanks for the reply and I am beginning to understand but with only 3 sensors, (two front and one on the differential) how could the ETS know which rear wheel was spinning and apply the brake? Does it apply brake to each rear wheel equally?

I think its more like an LSD (Limited Slip Diff). Its not really braking its just shifting the torque over but doing it electronically.

What I am not clear on myself is if you have ETS and ASR does that mean you have 5 sensors? I don't know :confused: :)

Thanks for the reply yal. Now I'm getting more confused :confused:

<<The electronic traction control system, or ETS, prevents the driven wheels from spinning on a slippery road by applying and releasing the brakes electronically. This provides better traction when starting off and greater stability when accelerating or cornering at low road speeds. At higher speeds, the ETS lamp comes into operation to warn the driver that the physical limits of adhesion are reached. The electronic traction control system is fitted as standard in all E-class models.

Acceleration skid control, or ASR, prevents the driven wheels from spinning or the car swerving due to excessive acceleration. Compared with ETS, ASR offers a broader scope of functions.

When either or both of the driven wheels threaten to lose grip, ASR controls the engine and brakes automatically by reducing engine power and braking the affected wheels. ASR is optionally available >>

This is the newer E system, but it explains the difference..
The basic plus of ASR is that it also controls throttle inputs.......not just wheel spin braking