W126 Stereo Connections

[S11YBM]

Somewhere down the line, someone chopped of the original stereo plug and wired in a 12 pin pioneer one. Now the pioneer stereo is not working and I want to replace it.

How do you guys suggest I go about doing this properly? I'm thinking of wiring in a iso connector, has anyone done this before?

 

[S11YBM]

Any one?

 

[Norte23]

As long as you can match the car loom to the correct pins on the iso it's not a problem. I might have an iso with wires on in my work shop I could send you.

Mark

 

[S11YBM]

As long as you can match the car loom to the correct pins on the iso it's not a problem. I might have an iso with wires on in my work shop I could send you.

Mark

Thanks Mark, thats much appreciated! Is wiring up an ISO the best way to go? I'm assuming that would give me the flexibility in choosing a headunit?

 

[grober]

What's the model number of the PIONEER STEREO unit?
e.g.
http://www.tehnomagazin.com/Auto-radio-car-connector/PIONEER-Car-Radio-Wiring-Connector.htm

you could try your local Maplins for iso plugs?
http://www.maplin.co.uk/p/hama-universal-iso-plug-set-02m-a45fl

 

[S11YBM]

What's the model number of the PIONEER STEREO unit?
e.g.
PIONEER Car Radio Stereo Audio Wiring Diagram Autoradio connector wire installation schematic schema esquema de conexiones stecker konektor connecteur cable shema

you could try your local Maplins for iso plugs?
Hama Universal ISO Plug Set 0.2m | Maplin

The model number is DEH-524R, from your link its same as PIONEER DEH-P443R (i.e.http://www.rcl.lt/?id=2&lang=en&begin=0&acc=show&fid=846&pcode=CJL8A11/ISO&pmode=) So I should just follow that and match the wires on the iso connector..

 

[grober]

plug wiring is almost certainly going to be the same as the DEH-624R in that link I posted.
you might want to use a multimeter on DC volts to test for the permanent +12 volt line and the ignition switched +12v line [ use a chassis earth for negative lead rather than the plug earth] until you orient yourself

ps Mercedes wiring convention at that time meant earth wires were brown.

 

[S11YBM]

plug wiring is almost certainly going to be the same as the DEH-624R in that link I posted.
you might want to use a multimeter on DC volts to test for the permanent +12 volt line and the ignition switched +12v line [ use a chassis earth for negative lead rather than the plug earth] until you orient yourself

ps Mercedes wiring convention at that time meant earth wires were brown.

Thanks again. And to confirm, its best to go for an ISO connector rather then something else?

 

[grober]

Thanks again. And to confirm, its best to go for an ISO connector rather then something else?

Iso connectors are the best choice for European cars and probably offer the widest range of head units that should be plug and play--- but always check the head manufacturers install instructions!

 

[S11YBM]

Over the weekend I got the iso connector wired in, thanks to Mark for sending over the iso connector.

Slight issue which I've not had a chance to in to yet, the rear speakers do not work. It seems like the PO installed new speakers in the rear parcel shelf and disconnected the fader. I'll start of by tracing the cables from the "new" speakers (on the parcel shelf "lids"). I'm thinking they are connected to some kind of amp as the wires that connect to those speakers are different to the ones that connect to the head unit..

 

[grober]

There's a diagram for a typical fader/amp circuit of the time in this thread
. 1989 300SEL Audio System - Mercedes-Benz Forum

As suggested in the article the newer tuner head amps may be capable of driving the rear speakers directly from the head unit rather than thro any old amp setup altho they may have used the old amp wires to connect up the REAR speakers You need to trace them basically to find the "join" or the amp [old or new]

ps matching speaker impedance may be a problem

 

[S11YBM]

There's a diagram for a typical fader/amp circuit of the time in this thread
. 1989 300SEL Audio System - Mercedes-Benz Forum

As suggested in the article the newer tuner head amps may be capable of driving the rear speakers directly from the head unit rather than thro any old amp setup altho they may have used the old amp wires to connect up the REAR speakers You need to trace them basically to find the "join" or the amp [old or new]

ps matching speaker impedance may be a problem

Thanks Graeme, will report back once I've had a chance to look.