If this is for your 1990 it's just asking for the code. Once you have it simply type it in number for number with the 1-0 buttons. When you enter the correct code the radio will come back to life.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

You don't have to cut and splice. You can get a set of plugs to mate with MB factory wiring from them for $20-30 or so . I just did for my 87 190TD. cheers Dan

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It's always something simple
91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
02 Golf TDI new head courtesy of PO
87 300D
97 BMW 525 TDS Wagon 5spd
bunch of Onan and other diesel generators

2x on using adapters. There is never, ever a reason to cut up the factory wiring. Moreso on your 1990 where the speaker and antenna lead actually go to the head unit...

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

Sorry for the plug misinformation. Last time I was working with these, I couldn't find that when I needed it.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL