argghhhhh! amateur shop. if our m-b sytems were purely mechanical, then i would use a door lock solenoid in the door itself (volvo, vag are some). on our m-b, the wire for the electrical impulses (reversing polarity) can be located either:
1 wire by the kick panel
1 wire by the vaccuum motor itself (rear seat).
my advice? take it to a shop that has good knowledge with m-b's!
i worked 6 years as an electrical tech for auto shops. at 1 shop for 2 years, we worked with the m-b dealer in san francisco. m-b are really easy to work on if you know what your doing.
92 W124 300TE -- new to the family
85 W460 300GD Biodiesel -- going and going
98 W210 E300 Biodiesel -- 200k and going
86 W201 190E 2.6 stroker 16V -- RIP