Well after 146K miles I'm blessed with no electrical problems until now. When I shut the car off the radio keeps playing,& the ant. does not retract, when I shut off the radio all works as it should, any ideas, I have the electrical trouble shooting manuel, but I thought just maybe you might have an idea.
Thank you in advance, Chris C.

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This & most M.B. radios have several "power" sources. Sounds like the source that happens w/key on isn't getting to the radio. Does the glove box light & the Cig. lighter Work?? They are on the same circuit(fuse).

If the fuse is blown, I have seen the wires for the lighter broken and grounding out. They move on this car when you open/close the ash tray.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I had a similar problem on my 1993 190E 2.6 a few years ago. It turned out to be a shorted diode in the circuitry that provides power to the drivers seat when power is off and the door is open. It allowed current flow (back through the diode) into the Accessory Circuit which powers the radio. I replaced the diode (I used a 1N4007 as I stock these) and all has been well ever since.

Regards, KM

300Es have a diode for accessories when door is open. It is located in the relay box behind the fuse panel. It is a grey 2pin at the very back (and hard to get to). It can be tested with any multi-meter capable of diode testing.

Thank you all, this weekend I had time to look, theres 4 wires that connect to the cig. lighter 2 were open (busted)... I don't smoke but the ash tray serves as a change holder, it gets used alot.I had a couple of female spades and some shrink tube,done deal... Thanks again, being pointed in the right direction saved me hours! Chris C.

Is this diode easy to install and where is this part that you mentioned available? We have a '90 300E and have checked out the wires near the ash tray and all the fuses. Live in Washington near Portland, Or