Hmm, I can only tell you how it works on my car without the 883 code
(no Close Assist). The black line from the PSE pump, under the rear seat
handles both flap unfold/retract and trunk release. I guess the trunk release
is followed by the unfolding of the flap driven by the same pressure
(or vacuum?).

br,
syljua (wanting to buy retrofit kit 1407500584, but oh, so expensive...)

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1998 CL500 W140
1984 230E W123