Hello, New guy here.
We have two Mercedes cars now and the one below is our third.. We've had an 81 300SD since 92, a C240 4matic wagon since last year. The 300D came up from an estate sale of a gentleman that we knew. Only has about 68,000, one owner, kept in garage. Couldn't turn it down. This bit of an electrical problem is about all I know of that is wrong.
Just purchased an very nice 300D which seems to have an electrical system problem.
If the battery is hooked up the battery light on the panel lights up even when the ignition switch is off. When turning the switch on I do not see the glowplug light or any of the others however the car starts fine and runs fine of course. Stops fine when I turn the ignitin switch off but the red battery light stays on and according to the previous owner it runs the battery down. This is my third Mercedes and I've never seen this problem before.
Any help would be appreciated.
Thanks and glad to be here.
Gary Porter
Fairbanks, Alaska

 

Hi I have the exact same problem here: battery light always stays on even when the engine is shut off and glow plug light is off when i turn the key in the ignition. Have you found a way to solve the problem? Thanks

 

I had a similar problem and I found the Voltage Regulator, the one in the back of alternator, not working properly.
In my case the voltage generated by altenator was not crontolled by regulator. I bough a new one installed and the problem was solved.
I hope it can help.
Good luck.