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Discussion Starter #1
Lately I have noticed a few things that don't seem right on my 2010 SL63:
I occasionally feel the lumbar support in my seat changing shape without any input from me, while driving or stopped at a light.
The trunk, when using the close button, slams rather loudly. I think it used to close softly and quietly.
I seem to hear a pump running more often when I first start up the car.

Could this all be related to the air system that operates the locks?

Sorry, if this has been covered already. I would have searched for answers, but the forum search functionality seems to have disappeared with this new interface.
 

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The bladders within the seat for the lumbar support are filled and emptied by the pneumatic pump, but apart from the act of locking the trunk lid is closed by the hydraulic pump.
 

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You probably have a slight leak in the seat bladders or pneumatic lines. The seat controller will activate the PSE pump to refill the bladders when it detects they are not at the desired inflation size.

My trunk has always slammed when using the automatic closer. Like Bobterry said, the trunk lid is operated by the vario roof hydraulic system, so that is totally unrelated to the seat bladders. However, the trunk latch itself lock and unlocks via the PSE pump. Alll that does it pull the lid down the final half-inf after it has been slammed shut by the hydraulic system.

The noises you hear are possibly two thing. A loud pump sound from under the hood is the SBC system for the brakes. It is normal that it activates when, say opening a door. Anything that wakes-up the car's CAN buses will cause SBC to do a quick check, and if it needs to pressurize the brake fluid, the pump will run. It will also run as you drive, but you probably won't hear it over the engine. The other thing is the PSE pump in the trunk. It's fairly well insulated and buried, so it won't be very loud, but sometimes you can hear it operating. If it runs a lot or you hear hissing around the trunk latch, then it (the latch) maybe bad. They are prone to getting cracks int he plastic housing and leaking.
 

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Discussion Starter #4
You probably have a slight leak in the seat bladders or pneumatic lines. The seat controller will activate the PSE pump to refill the bladders when it detects they are not at the desired inflation size.

My trunk has always slammed when using the automatic closer. Like Bobterry said, the trunk lid is operated by the vario roof hydraulic system, so that is totally unrelated to the seat bladders. However, the trunk latch itself lock and unlocks via the PSE pump. Alll that does it pull the lid down the final half-inf after it has been slammed shut by the hydraulic system.

The noises you hear are possibly two thing. A loud pump sound from under the hood is the SBC system for the brakes. It is normal that it activates when, say opening a door. Anything that wakes-up the car's CAN buses will cause SBC to do a quick check, and if it needs to pressurize the brake fluid, the pump will run. It will also run as you drive, but you probably won't hear it over the engine. The other thing is the PSE pump in the trunk. It's fairly well insulated and buried, so it won't be very loud, but sometimes you can hear it operating. If it runs a lot or you hear hissing around the trunk latch, then it (the latch) maybe bad. They are prone to getting cracks int he plastic housing and leaking.
Thank you. That is helpful.
 
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