Hi Jeff,

ABV stands for: Anfahr-Brems-Verzögerung (Accelaration-Decelaration-Delay). By using this function you have the decelaration and accelaration under direct control. If you don't see any difference it probably has to do with the settings of your decoder, if (in normal mode, f4 off) the loco does not brake and accelarate slowly you will probably not notice a difference if you shut the ABV off.

Hi Jeff,

you might want to reset the decoder of this loco or simply change the acceleration(ACC)/deceleration(DEC) to a desired value by you; factory default settings are 3,48s and 2,61s.

When pressing f4 the loco should react quite direct upon changes of the speed knob. Mine for example takes nearly two track lenghts (about 30cm) from medium speed (150/step 8) to 0 without the ABV button pressed and about 5cm when the button is active.

Lutz,
You are correct indeed. I just tried it again and there is a noticable difference in deceleration with F4 depressed (works just like the rest of my Marklin digitals..). My first reaction was to look for some other condition based on the description. If they had said something like "Acceleration/Deceleration Brake delay off" I would have picked it up immediately. Oh well, such are the ways of M*..
Thanks again,
Jeff