RE: Indicator problems on an 02 E220 CDI - help!
I suspect water has got into the electric at some point. Vehicle history. Carwash? Had the car valetted? etc.
Flashers and other electrics on your car are digital.
Either the CAN which connects the various modules has a poor connection / or water in a connector or th LH (Fr or Rr) SAM (Signal Acquistion Module) has a similar type problem.
Digital electrics are not for the DIYer unless you like a challenge and understand how digital works.
Best route is to get the vehicle plugged into STAR diagnostics (MB Dealer) and observe codes (different scanner required to simple engine codes) and observe code.
Of course you COULD possibly save money by quessing which module or connector has the problem (the source of the problem could be ANY module...there are lots = 25+... plugged into the CAN or the CAN itself) and buying a new unit but this IS LIKELY to prove to be the more expensive route!!
Not sure of the location of the modules on your model but as a straight guess I'd look at the LH door/mirror control switch (I assume your controls are door mounted but may be wrong here)