Hi everyone,

I had an aftermarket stereo installed in my '89 420sel along with new speakers and speaker wire. I had the Becker unit rebuilt and would like to re-install it.

I can't find a diagram or anyone who seems to be able to provide a general idea how this system is wired. The fader was "cut from the loop" and I would like to use it again if possible.

Any information would be appreciated. The guy from Becker said they do not have diagrams and 3 Mercedes dealerships said the same thing.

Thanks in advance for any information.

You just need the wiring diagram for the "radio" for a 1989 model W126. They will all be the same. The FSM has it, or you can find it on the Startek site or Google should provide the answer. The factory wiring isn't anything special, whoever says they can't get the info on it is either lazy, ignorant, or lying.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Thanks for the reply.

I have searched google and have not found anything to date.

I'm not sure what FSM is. Can you elaborate?

Startek says from 1994 to present unless I am accessing the wrong site.

FSM is shorthand for factory service manual.

W126 is available here: https://www.startekinfo.com/StarTek/outside/12253/?requestedDocId=12253

I've attached the relevant pages for your model as a PDF below. 1988+ seems to have a fairly complex system.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

This is a big help - thanks for the information.