I think pag nasa 2, based on honda autobox, naka stuck siya sa 2, as in mag start siya to roll from a stop position on gear 2.( that is to prevent wheelspin, kung slippery ang condiotion. e.g. icy, muddy.)

pag pababa kung gusto mo mag engine brake, either you switch o/d OFF, or kung may d3, use d3.