W126 rear speakers

[jkeith]

I'm puzzled to understand why my rear speakers do not work. Was this model (300 SE) supplied with wiring only to the front speakers? The recently acquired car was supplied with a Sony unit fitted and a Blaupunkt Melbourne SQR 39 as the 'original'. Neither unit appears to have any rear speaker balance.

I'm working blind in that I do not have any wiring diagrams.

Any help would be much appreciated.

 

[ianrandom]

have you got the fader dial in the centre console of the car near the window switches?

 

[jkeith]

No fader dial fitted on my car. I did specifically check this having seen reference to such on a W124 on another thread. Mine is a 1989 car.