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 C240 Wire Connector on Transmission May Leak Fluid and Damage Control Module
Mercedes-Benz C240 Problem
Average Mileage: 74,751 mi (39,254 mi - 144,000 mi)
Transmission fluid leak. Initially diagnosed as 13-pin connector failure. Replaced. Leak still existed. Diagnosed as needing to replace tran electrical conductor plate and 13-pin connector. Leak fixed.
Visitor, 2003 Mercedes-Benz C240, 39,254 mi
Purchased 2002 C240 used with 27000 miles.Told the dealer that a small ATF leak at the 13 pin location required fixing before the purchase. They told me they fixed it by tighting the connector. The leak progressed and showed up on the garage floor. I replaced it today with a ATF and filter change. Looks like someone had worked on it before because the harness was routed up and over out of the faseners. This is part of Mercedes TSB fix it.Found the old red O rings in the connector and replaced the complete connector with a new MB product and ATF 134. Everything seems ok but haven't checked it today. Can't believe MB didn't provide a recall for this . Seems like it happens to all of 722.6 tannys.
Visitor, 2003 Mercedes-Benz C240, 144,000 mi
Repaired leak, replace module etc.