Hello Scirocco,
I assume the light on the dash is not the triangle. If not, then when does the "4matic" mil come on. It will remain on if the switch is in the workshop position. It will remain on if the pressure switch senses no hydraulic pressure from the tandem pump. The light will remain on if there is a code in the system. A pressure problem may NOT set a code.
Don
(JM stay away from the buyer of my 96 E300d with that buy-back bs. I know where you live.)

__________________
When the people fear the government, that is tyranny. When the government fears the people, that is liberty. -- Thomas Jefferson