Originally Posted by fgwinn

I installed an aftermarket sensor in my 2005 SLK350 (since traded in on SL). I posted some pictures on the benzworld forum. I was able to "tap" into the backup power by modifying the backup light socket. When I first tried the unit without a bulb in place, I did get a burned out bulb message on the display. With the bulb installed, the unit worked fine. I speculated that the backup unit was not drawing as much current as the bulb.

I suppose it is possible that the unit you have is drawing too much current and causing a different error. You may try using a low current relay to isolate the backup power supply from the backup circuit itself.