The electrical connector at the automatic transmission may leak fluid into the wiring harness. If not repaired, the oil will migrate through the wiring harness and damage the transmission control module. At that point, a new harness and control module may be necessary to correct this problem.
Car Problem Reports
Mercedes-Benz S600 Wire Connector on Transmission May Leak Fluid and Damage Control Module
Mercedes-Benz S600 Problem
Visitor, 2003 Mercedes-Benz S600, 112,000 mi
Replaced gasket, conector, cleaned TCU with electric cleaner
Visitor, 2001 Mercedes-Benz S600
This problem happened three times. The transmission control unit filled with fluid from leaking ETC connector.
The Solution: They replaced control unit, locking pin, ETC connector plug, pilot bushing, trans.fluid