May the Gods of Shade Tree Mechanics bless and keep you.:wink
It has been over 50 years since I had a seat out, and there was no electronics then. I was apprehensive, but I am retired and just cannot afford MB's labor rates. The detailed instructions and pictures made this doable.
I was having an intermittent problem with the SRS lamp so I was sure there was a broken wire - someplace.
It took a while to get the seat out and exposed on a bench but it went well from there. I stripped the insulation of the 3 wire connector close to the end back at the seat. I then used a multimeter with a sewing common pin as a probe to poke through each wire's insulation doing a continuity test from there to the plug. All was OK until I pulled on each wire. The brown lead came out. Fortunately, the break was far enough out from the seat that I could splice it. A bit of Bench Tech work - stripping, soldering, shrink tube and it was done. SRS lamp now functions properly.
The break was right where the cable was tightly tie-wrapped to a passthrough on the seat steelworks. Definitely poor Manufacturing Engineering, the cable should have been able to flex freely. Note, this was a 2001 and the wires were stranded, not solid core.
Once again, Benzworld forum has saved me money.