Ryan,

Confirm with your mechanic what the specific name and part number of the module is that he is recommending you replace. From your symptoms, I wouldn't be surprised if the part is the EA/CC/ISC module (Electronic acceleration, cruise control, idle speed control).

This unit retails for about $788.00. We have seen several of these units fail on M104 Motor cars with a little over 100,000 miles. They somtimes fail in conjunction with the throttle slide, another extremely exprensive part, which fails because of faulty wiring--just like the engine harnesses. We have started to jokingly refer to replacement of these three components as the "supplementary 90,000 mile service."

If your vehicle has been dealer serviced from new, you may get somewhere with Mercedes-Benz in terms of reimbursement for the engine harness. We have not had much success with our three local dealers if vehicles have not been dealer serviced, but it is always worth a try.

Good luck to you, and please let me know the part number of the unit which your mechanic is recommending you replace.