The electrical connector at the automatic transmission may leak fluid. Over time leaking fluid could migrate through the wiring harness and damage the transmission control module. If that happens a new harness and control module may be necessary to correct the problem.Google+
Car Problem Reports
Mercedes-Benz SLK230 Wire Connector on Transmission May Leak Fluid and Damage Control Module
Mercedes-Benz SLK230 Problem
Average Mileage: 91,733 mi (58,200 mi - 120,000 mi)
Visitor, 2000 Mercedes-Benz SLK230, 97,000 mi
Screw that holds electrical connector in place on the transmission broke off, had to replace the electrical board inside transmission to stop leak, now after a few months the transmission has blown fuse again and smoke came from TCM, now transmission does not shift and speedometer does not work. Replaced fuses but nothing happens was told I had to replace TCM and Harness.
Visitor, 2004 Mercedes-Benz SLK230, 58,200 mi
Transmission fluid leak through the electronic switch connection into the transmission case.
Visitor, 1999 Mercedes-Benz SLK230, 120,000 mi
Leaking from Control Module