Trunk doesn't open unless engine is running
 

2004 S430 runs great but in the last few months has developed a problem where if the engine is off the following don't work at least 80% of the time:

1. can't open trunk using remote control
2. can't open trunk using the trunk release on driver door
3. can't open trunk using the button on the trunk

In 20% of the cases, it works fine.

However if the engine is running, the trunk opens 100% of the time by any of the three methods above. There are no error messages.

Any suggestions?

Thnx.

check your battery and charging system!