no low beam
 

I have an 81 240D and the problem I have is no low beam on the drivers side.Voltage is good until I plug the light in then the Voltage drops to zero....any suggestions would ease my headache.....

No expertise in that particular model.

Generally, a good voltage reading under low load, followed by a zero voltage reading under load means a marginal electrical connection somewhere, often a poor ground, or dirty terminals. Start by wiggling the fuse, just to be sure, then clean and grease the terminals and ground(s). If all that fails, suspect the relay.

Recently had a similar problem on my boat, which turned out to be a hairline crack in the positive battery terminal plate. Very unusual problem. Sure was tough to track down!