yup, i think that wire goes to the locking cylinder which triggers the locking/unlocking and rolling up of windows. At least that's how it is with the 124. I do have a w140 that is currently "interior-less"... i can trace that wire for you when i get home... only ISSUE is, my car didn't come with the infra-red control thing... though i'm pretty sure the trigger for lock/unlock/window is the same. will let you know in 3 days.

i'm working OT
they probably cut it so the alarm module doesn't get confused. they wired it in such a way that the module has total control over the locking pump.
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85 190E 2.3(SOLD)
86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
87 300TD (SOLD)
95 S280 "The KRAKEN" (Turbo 2.9 602 transplant) traded
86 190E 2.3... current project