Take the foot off the brake pedal, John. Braking switches 4ETS off in pre 02 MLs. Here is a demo with the brake lights lit up and the wheel spinning. Once the foot is removed from the brake pedal the ML moves off this spot - with the wheel still in the air. One of my favorite ML exercises.
Also, in idle 4ETS won't work either and the wheel will spin freely, rotating slowly at idel rpm. One needs to put the foot on the gas pedal, even with very little gas, and 4ETS will engage and the wheel in the air stops spinning.
