Does it have fog lamps? If so, does the light switch have a way to turn on just fog lamps, or parking lamps with just fog lamps? On both of my MB's, I use the fog lamps as DRL's. On the 81 300D (W123), I had to "reconfigure" (change a couple of wires on the switch & add a relay) so that I turn the switch one click clockwise to operate parking lights & fogs only.
On the 91 350SDL (W126), I merely turn the switch one click clockwise & pull it out to operate fogs without headlamps.