This is the ISM module saying hello, for some reason.
Something is severely impacting your CAN-C coms.
It can be caused by electronics soaking or normal low voltage - (NEVER drive through standing water: CAN-C VIP harness located all the way at the lowest, near single GND strap!)
Connect a scanner to read current chassis faults. Beware of silent missing modules.
> There's a remote chance this can be caused by a low battery voltage. 🤞
In any case... do charge your main battery with an automated charger.
I get the message every time I flash my ECU with a tune file. Flashing requires erasing the ECU and loading a file with new parameters. It's during that erasing process that I get that message.
I would seriously consider get a BenzNinja Club membership (www.benzninja.com) and have Peter (BenzNinja) remotely scan and diagnose your problem. However, you need an SDS setup with a C4 Multiplexer and Laptop. BenzNinja provides the XENTRY software on an SSD that he sends to you to install on the laptop. That takes a little time, but he does rent equipment for the short term while you assemble what you need.
The dealer may want to replace your ECU, so consider BenzNinja as a possible alternative.
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
