Trunk Close Assist
Thread Starter
Newbie
Joined: Jan 2013
Posts: 6
Likes: 2
From: Buffalo, Ny
'99 CLK320, '02 ML320, '96 S500, '09 CLK550, '99 E55
Trunk Close Assist
Hello all,
if anyone can shed some light on this one, I'd appreciate it. Been combing the threads and couldn't find anything on this specifically....
On my S500, I have had a parasitic battery drain for years and haven't been able to figure out what is causing it. I have pulled every fuse and relay and used a test light to see which circuit was open, but this method did not work. The drain isn't too bad: if the car sits for about a week, the battery will usually be dead when i go to start the car. But if driven everyday, you wouldn't know there is a drain. After doing some thinking, I am wondering if it is being caused by the vacuum pump in the trunk possibly. The reason why I say that is sometimes I have randomly noticed that the chrome handle for the trunk's close assist will be stuck out, even though the trunk is closed. If I open the trunk and close it again, the close assist will draw the handle back into the trunk like normal. Also, the vacuum that draw the trunk closed has never worked to my knowledge since I've had the car. From what I've gathered... it sounds as though there is maybe a serious vacuum leak, that makes the pump randomly engage the handle, and/or the pump may have lost some functionality and has possibly burned out partly. Would this be a fair assumption to think this is causing the drain?
if anyone can shed some light on this one, I'd appreciate it. Been combing the threads and couldn't find anything on this specifically....
On my S500, I have had a parasitic battery drain for years and haven't been able to figure out what is causing it. I have pulled every fuse and relay and used a test light to see which circuit was open, but this method did not work. The drain isn't too bad: if the car sits for about a week, the battery will usually be dead when i go to start the car. But if driven everyday, you wouldn't know there is a drain. After doing some thinking, I am wondering if it is being caused by the vacuum pump in the trunk possibly. The reason why I say that is sometimes I have randomly noticed that the chrome handle for the trunk's close assist will be stuck out, even though the trunk is closed. If I open the trunk and close it again, the close assist will draw the handle back into the trunk like normal. Also, the vacuum that draw the trunk closed has never worked to my knowledge since I've had the car. From what I've gathered... it sounds as though there is maybe a serious vacuum leak, that makes the pump randomly engage the handle, and/or the pump may have lost some functionality and has possibly burned out partly. Would this be a fair assumption to think this is causing the drain?
Last edited by BlackVinDiesel; May 25, 2022 at 12:08 AM. Reason: Left out key detail
MBWorld Fanatic!
Joined: May 2003
Posts: 4,005
Likes: 106
From: Houston, TX
2015 E250D
If the trunk handle sticks out after closing the trunk, the most likely issue is the contact switch located in the base of trunk where the eye latch goes into. There is a small switch that which sends a signal to the pump located under rear seat to suck the handle in as well as turn the trunk light off. The pump located in the trunk itself is for all the soft closing functions such as doors and trunk lid (but not the extendable trunk handle)
