I suspect an issue with the stalk switch, or possibly the contacts in the wiper motor that tell the motor when the arm is in the parked position. I haven't had a chance to consult the service manual, but will be later today.
Gettin' a bit new for me, but on an '86 SL I found that somebody had kicked the wiper 'relay' and broken it off. It wouldn't do the intermittent thing, nor would it park. But it always did shut off with the stalk switch. So, based on _that_ car I'd say that your problem was the stalk switch, and that a shot of Caig Deoxit right in the gizzard might do wonders.
(I glued that SL relay back together and bridged the broken traces with wire and solder. Worked fine since then.) -- Jim _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com