1987 SL380 can not open trunk
 

1987 SL380 battery is dead, can not open trunk to charge battery.
Trunk usually operate by vaccume, tried with key do no work, tried with
battery charger to cig lighter with key turn on still do not open.
Please help...:ukliam3:

You need to start the car and let it run for a minute to build up some vacuum.

See this post -

http://www.peachparts.com/shopforum/vintage-mercedes-forum/202450-1976-450sl-coupe-trunk-will-not-open.html

Look in the engine compartment on the passenger fender and you'll see a black plastic cover. Open that up and you'll see two very large cables that join under it. That's a straight shot to the battery in the trunk. Hook your charger's positive up to that junction and the negative cable to the engine block and let it sit to charge. Once it's charged enough to start the car you'll have vacuum to open the trunk.

Then I'd look at the trunk lock to see why you can't open it with the key. That's a problem.

Vacuum lock
 

The trunk should open with a lack of vacuum on the system. If you can get to one of the vacuum lines remove it and bleed the vacuum from the system. The trunk should then be free to open.

Otherwise, I have read on one of the forums someplace there is a trick to opening the trunk with the key if it is fussy. Do a search and you may find some pertinent information.

Good luck!!

still looking for how to get in on 560sl. already disconnected the vacume system and had to use the key,when key stoped working. a shop drilled small hole behind license plate, and got it opened. worked for a yr and same problem. I can't duplicate their success,and now battery is dead so can't drive there,gas turning bad. etc. anyone drilled out the trunk tumbler?

Well, look at the post a few above - you can charge the battery from under the hood.