When you turn the wipers on in that car, there are 3 computers involved!
If you leave the wiper switch in the "auto" position, there are 4 computers involved!

To diagnosis that problem on that model & MOST MB's after 1998 you would need a MB scanner capable of reading codes from those computers & capable of reading live data & activation of that system.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator