I have a 78 300CD and my central locking system is temorarily out of operation. You said you can't get in with the key? Bummer! Are you turning the key past 90-degrees counter clockwise? Mine works with the key but won't stay unlocked, but to use the key to open it you insert the key and turn counter clockwise from 12 o'clock, past 9 o'clock, to about 7 o'clock and push the key in. This should mechanically open the lid.

If this doesn't work, I'm fresh out of ideas. Don't try going in from the cabin by removing the back of the rear seat, it won't work, besides the fuel take sits behind the rear passenger seat and separates the trunk from the cabin. In worse case, I'd probably go with a tungsten sidecutting bit on a dremmel and replace the lid. As I said, last case!

Try the key thing one more time and good luck!


Scott