It sounds like a 90 or 91 with the test lever. Upon startup, the 4matic light should blink / flash a number of times to give a code. If it does not, try disconnecting the battery for a few minutes and then restart to check for codes. The test lever should be down (in the operating position) and make sure you have fluid in the 4matic reservoir.

The codes will tell how to start troubleshooting.

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126