Mercedes E240 keyless Control System can't response properly

One Mercedes E240 car made in 2008 year with 65 thousands mileage, the driver describes: the KEYLESSGO function (keyless Control System) can't response properly.

Benz e240 2008

Diagnose fault: after test, I find when I use KG (open and lock doors with keyless go function) to lock and unlock the door, sometimes the KEYLESSGO system can't response properly, only after times trial can it work. Then I check WIS and find the rear KG control unit plays a vital role in the system, because it is hub contacting with KG card and EIS. According to the principle of the system, I exclude the possibility that the other 5 pieces of control units have problem, and focus on the EIS and N102. I use professional Mercedes Benz oscilloscope to test the data transmission system of control module. After many times trial, I find sometimes KG control module can't transmit the lock and unlock command information from the driver, therefore I work out the reason, it is the rear KG control module has electronic problem or software problem, and result in the above-mentioned problem.

How to solve the problem: Change KG control module, test the function, the fault doesn’t occur any more, everything work well. 

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