So I played around with my closing assist pump this evening.

[luxiglide]

Do's and Dont's with the close assist pump.

Following the info I have learnt bucketfulls in the last 24 hours.

If some doors work and others dont then remove fuse 9 in trunk. Faulty door/doors will work twice only, then fail.
If so problem is leak on pressure/vaccuum l;ine to each individual door.

Remove pump from its mounting on left of petrol tank in trunk, remove foam cover and find each each line labelled V = vor (front) H = hinter (rear) L = Left R=Right HR = trunk

Line to failed door will probably leak at the pump. Leak test with foamin agent (BIG CAUTION) do not get electrical connection wet as I did! (more later).

Bubbles were evident on one at two lines.

Removed line on each and applied trace of silicone grease. Re-assembled and used cable tie to create better "grab" for connector.

Leak tested again and bingo! no leaks and pump operates all doors perfectly.

Information:

The pump runs as both compressor and vacuum.
Compression is first action and the pre-set pressure switch in the pump is set to 3-bar (40psi).

If pressure switch does not actuate within pre-set time following door closure the pump assumes a leak and "times-out" that particular channel, leaving all other channels operating.

Once a door close has been sucessful the pump operates in reverse and a partial vacuum is pulled in the particular line to return the closer to the set position.

Hope this (combined with previous info) helps to unravel the mystery of this particular ki.

In my case I leak tested with water/washing-up ligquid. I let water accidentally spill on the the multi-pin connector to the pump and electrolysis did its worst, with complete failure of the pump less than 5 hours later!!! A salutory lesson.

Now does anyone know where I can get a new circuit board from? or who might be able to repair?

[Brett San Diego]

for "closing assist" you will come up with several other threads on this topic. One or two of them mention a guy who does pump rebuilds. I believe he is the technical forum editor for the Mercedes club of America magazine. His name is George, and an email address was given for him in these previous threads. I have it at home somewhere but don't have time to look for it now online. I'll dig it up this evening, if I remember. He may be helpful.

Brett