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Old 01-11-2013, 01:28 PM   #1 (permalink)
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Date registered: Mar 2005
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Question about vacuum/PSE pump...

Hey, folks.

I did a search on this and didn't turn up very much, just one thread that discussed epoxy and check balls and didn't sound like the same issue anyway.

Now that the weather has taken a sudden chill, the GF's 2001 CL55 has decided that the door locks shouldn't work.

When you press the remote buttons the alarm arms and disarms as usual, but the locks don't respond.

I'm assuming that one of the lines back at the pump is stiff/brittle and without the flex it's letting air escape. (Once the day warms up the locks work normally.)

On my W210, all we have is the PSE pump under the back seat and that runs everything. However, her car has a PSE pump under the battery, and then there is the large vacuum pump in above the LR wheelwell.

I've poked around in the EPC and haven't been able to discern what the driving force is in this thing.

So my questions, if you pros don't mind:

1. Which pump supplies the air to energize the door locks? The PSE or the vacuum pump?

2. Whichever one it is, has anyone taken one of these apart to inspect/replace lines/connections? (The W210 PSE pump can be disassembled and there is a main internal tube that turns brittle and leaks, then nothing works.)

Any other information you can provide would be much appreciated.

Thanks and enjoy the ride,
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Old 01-11-2013, 01:51 PM   #2 (permalink)
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Angry PSE Pump vs Hydraulic Pump


My understanding (search further on the forum to confirm) is that the PSE pump is the one over the left rear wheel and supplies all the pneumatics (locks, seats, etc) and supplies both air and vacuum in our CL55s (mine is an '01 as well). The pump under the battery is hydraulic and powers the trunk open/closing.

I've been dealing with a similar problem on my '04 S500 - locks and trunk - but haven't had time to resolve it fully. I think my PSE pump has died on me from it cycling too much (trunk lock actuator leakage).

Good luck,
"Dangerous with a wrench and not smart enough to know it"

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Old 01-11-2013, 02:21 PM   #3 (permalink)
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Thanks for the clarification, Kevin. At least I don't have to disconnect the battery (I just installed a new one for her after it failed some manner of test that MB threw at it, it was an aftermarket and was in the car when she bought it).

This thread over at MB world may be of some use to us both, with the caveat also that we carefully label anything we disconnect. Drivers door close assist feature not working - Forums

Thanks again and have a good weekend.
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Old 04-24-2013, 02:40 PM   #4 (permalink)
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Date registered: May 2004
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I just had this fixed on my 2002 CL500 (literally picked up the car from the dealer this afternoon).

The problem was a faulty PSE pump, so I can confirm Kevin's comments above that the PSE controls the pneumatics (including the door locks).

Cost me just under $1200. A close friend owns an independent repair shop, where I have most of my maintenance done, but in this case I wanted the dealer to do a full diagnostic to make sure that was the problem.

Hope this helps, and good luck. These cars are wonderful when they are running correctly, but seems like there are so many minor electrical and other issues that aren't cheap to maintain. That being said, I'm not ready to give mine up.
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