PSE running when changing gears, should be related
to the reverse parking aid poles on the back fenders.

The line for those are marked RH on the pump.

Do they extend or retrackt?

The one that you have traced is the vacuum supply
to the A/C system, and will probably run until
a certain vacuum is reached. Marking on that
is Pu or P-

br,
syljua

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1998 CL500 W140
1984 230E W123