http://i39.photobucket.com/albums/e166/lambodog/95%20Mercedes-Benz%20S420/SAM_0009.jpg

Look careful at that detachable lower left bumper grill, it slides in the grill

I'm having issues with it too. The sad part is that it doesn't have a connector, you need to cut the cable and attach the new one.
(unless you want to uncover the wiring harness and trace it)