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This is a follow up thread to the several discussions regarding an SL55 supercharger not engaging at the electromagnetic clutch. Thank you all for your sage advice--it helped immensely. While no one had the exact fix, you all got me going in the right direction leading to a simple solution. See the attached error codes.
I noticed a significant drop in power and suspected the SC. Sure enough, the clutch wasn't engaging. I read one thread here suggesting it might be a diode in the connector, but ruled that out after inspecting the connection. No diode was present. The relay "Q" tested fine as well, someone suggested that might be the issue. The fuse was fine. Several threads thought the electromagnet was dead. That seemed likely. Several threads here and Youtube suggested to do an unconventional repair by heating the SC shaft after removing the bearing and clutch housing that engages the SC belt. Some suggested heating the shaft and removing the magnet without removing the entire SC. I was just about to try the removal using the heat approach with the SC remaining on the engine.
My local Mercedes repair shop that I trust wanted to install a rebuilt SC at $4k or a rebuilt nose a $2k--leading me to bring the car home to try the heating method. Then I read a blog here and someone reminded me to first do the simple thing and test the magnet. Easy enough, wish I had thought of it earlier or better the mechanic. Unplugged it (the plug is just behind the clutch housing), put 12v directly to the magnet on the right polarity after researching 12v was the correct voltage and bingo, it engaged.
Traced the wiring back the fuse box (under hood passenger side, next to battery) and wires and fuse were fine. Fuse was to be in f44 location--see attached fuse location and description detail. Here's the fix--Mercedes changed the location of the SC magnet fuse in later versions of the car. It was the darn fuse located in f45--not the one stated to be in f44 which was fine. Changed the fuse and the SC now works fine. F45 also serves as the fuse for the O2 sensors. Check engine light is gone. Moral of the story--check all the fuses and don't pay the $4k until you've done so. I hope this helps next the guy,
Thanks again everyone, couldn't have figured it out without all of your help and suggestions.
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