R170 SLK32 2002 instrument cluster failure.
 

Out of the blue the instrument cluster failed, in the morning none of the gauges worked, the dash lights did not work nor did the LCD displays.

I tried to scan the cluster with a iCarsoft MBII and it could nto communicate.

Disconnected the battery and waited 30 minutes, reconnected.

Now all the warning lights (abs, srs, battery, steering angle, etc) are all on, the gauges and displays do not work and the idiot lights stay illuminated even 30 minutes after key out or ignition.

Disconnected the battery and waited 30 minutes, reconnected.

Back to none of the gauges working at all but at least the lights are not illuminated.

The turn indicators and emergency flashers work and the indicator on the gauge cluster works, the battery and SRS lights come on with the key in pos-1 but after start go out. The AC and all other systems function.

Battery is new, alternator is charging at 14.1 vdc
All grounds are clean, and I checked the plugs on the instrument cluster.
Turning on the headlights will not turn on the instrument cluster lights...

8 hours later - everything back to normal, this lasted a day. During this time I was able to communicate with the instrument cluster via iCarsoft MBII.

This morning I am back to no gauges or displays and now when the engine is running, the electric cooling fan on the radiator comes on full speed and remains on until the motor is shut down.

Instrument cluster???

On other cars, constant radiator fan is a default if there is a loss of CAN communication between the engine computer and ran controller.

I'd be looking at common grounds under dash and under hood. This was a problem on late 90's E class and could be on yours. Also, I " think " these cars had a problem with water intrusion under the passenger side of the dash that would affect the CAN network.