I read the DIY, and on a scope, duty-cycle is obvious.
But in a meter (modern-new-fangle-ones-with-chip) it can
do the area integration under the square wave, and print
out a percentage. But there still must be some max voltage,
less the meter becomes fried if it is hit w/ giga-volts.

Years ago w/ galvanic meters (iron core, needle stuff) we
could set the thing on a A/C scale, and the bridge inside
would integrate the areas under the curve for the + and -
voltage swings. If the cycling was fast enough you would
get a ratio, and a needle swing. But if it is a wave from
(say 0 to 12v dc) then this Rube-Goldberg will not work,
and you truly need the new (intellegent) meters, or a good
old fashion O'scope.

And I did put an LED across a pin in X-92 and read a code
of "12". But my Chilton book only has codes for the M103
engine to 10. Is there a list of codes somewhere within
this MercedesShop, or Forum????

Thanks!