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 S430 Wire Connector on Transmission May Leak Fluid and Damage Control Module
Mercedes-Benz S430 Problem
Average Mileage: 99,285 mi (73,000 mi - 150,000 mi)
Visitor, 2002 Mercedes-Benz S430, 108,000 mi
Just had the transmission control module replaced by the dealer. Wasn't cheap, $955.00 including parts and labor.
Visitor, 2000 Mercedes-Benz S430, 73,000 mi
leaking transmission by the plug,so now i am going to change fluid along with the plug when i purchase it
TRANSMISSION IS LEAKING FLUID GOT VEHICLE DIAGNOSE TO BE TOLD THAT CONNECTOR IS LEAKING HAVING IT FIX - KNOWING ITS GONNA BE EXPENSIVE
Visitor, 2000 Mercedes-Benz S430, 79,000 mi
I have the same problem and car has been in the shop for over 6 weeks. Really
Visitor, 2002 Mercedes-Benz S430, 85,000 mi
I had the same problem with the TCM. I had the conductor plate replaced and the TCM was cleaned of all oil. After that, the transmission worked fine but the ESP, ABS, SRS, and BAS lights continue to stay on. The vehicle is in the shop now (again) to correct this problem with the malfunctions.