Proven method? Sorry. I can tell you that undoing one of the tabs should work; if can get to one of the tabs w/ a flat-blade screwdriver, the swtich should pop right out.

As to your main issue, I can't think of anything else to check w/ the switch or the wiring, so back to the basics (I find simple stuff usually ends up being the problem when I'm in situations like this): 1) I'm not sure which ignition position is the "run" position; is that the position which will energize the fuel pumps? If not, have you tried the ignition in that position? 2) Have you tried both combinations of pins and receptacles?

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1990 190e 2.6 - The only one I can really call "My Car".

1987 190e 2.3 - The donor car's up and running, only mods are Euros and a Sony headunit. My Dad's runabout now.

1990 300e 2.6 - The parents' ride.