Wires On The Back Of My Head Unit

Discussion in 'Electronics' started by DSLiverpool, Aug 15, 2008.

  1. DSLiverpool

    DSLiverpool Hardcore MB Enthusiast

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    I pulled the pioneer to find a less than classic installation - I have most of it sussed (like put the plugs into the new loom) however the orange wire thats a direct connection is what ? the brown wires in an unsed plug are what please

    Dont want to blow the old girl up now she runs so schweet :rolleyes:

    [​IMG]
     
  2. Shude

    Shude MB Club Veteran

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    The orange wire looks like it might have an in-line fuse taped up with it so that makes it either 12v permanent or switched. A multimeter could answer this in seconds.
     
  3. OP
    OP
    DSLiverpool

    DSLiverpool Hardcore MB Enthusiast

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    Shude its more of a why is it there as well as a what is it - why would it need an external 12v perm ?
     
  4. Diesel Benz

    Diesel Benz Hardcore MB Enthusiast

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    I think Shude said switched or permanent. Since the OEM radio typically does not have switched power, this was likely wired for the new unit.
     
  5. Shude

    Shude MB Club Veteran

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    ISO connectors have a pin for both but they're sometimes swapped and sometimes they're both the same of either!
     
  6. OP
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    DSLiverpool

    DSLiverpool Hardcore MB Enthusiast

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    all done - the orange was a switched illumination pos to dim the pioneer and the brown was for steering vol control (I dont believe that but thats what I was told)

    My Sony now works great but looks horrible BUT I HAD to have the bluetooth facility and the Sony was free with credit card points !
     
  7. Shude

    Shude MB Club Veteran

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    Glad it's sorted! Orange is an odd colour for the illumination wire, I thought they were blue with a stripe and steering volume control sounds odd. Could be a speed pulse for speed-sensitive volume control?
     
  8. hitenhirani

    hitenhirani Hardcore MB Enthusiast

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    orange is quite regularly used for dimming/illumination.
    the brown steering control/volume could be true. its just a different value of resistance behind each button, and the unit will sense the current going in, and will determine if its volume up/down depending on signal received. its very weird i know, but 'tis the case on many car radio systems.
     
  9. andy27168

    andy27168 Hardcore MB Enthusiast

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    Blue with white stripe is normally amplifier trigger feed.
     
  10. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    my car has orange for the dimmer too
     
  11. richard

    richard Authorised Forum Sponsor Authorised Forum Sponsor

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    The pair of browns (brown-red & brown-white from memory) in the C connector is the car's CANbus (network) - its used for the head unit to know whether ignition is on/off lights on/off, etc etc, including the steering wheel controls, cluster display etc - its also used for just about everything in the car to communicate with all the other bits of the car -

    So the 'used for steering wheel controls' is partially correct, dont cut or short them, you will mess up your car a lot.

    Richard
     
  12. Diesel Benz

    Diesel Benz Hardcore MB Enthusiast

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    I guess this is the R129 car? I don't think I have the wiring and don't even know what car exactly it would be but it probably is close to the W210 wiring where:
    A-connector, pin 8 is ground, brown wire,
    pin 4 is constant power, red/white wire,
    pin 3 is the mute signal, yellow/black wire,
    pin 5 is the antenna power wire, blue/white

    Cars up to 05/99 also have illumination "signal" on pin 6, grey/blue wire,
    speed signal on pin 1, green/black wire and
    switched power on pin 7, black/yellow wire.
    D2B head unit would have a diagnostics line on pin 2, grey wire (wake up on C connector pin 4, blue/black wire).

    Can bus from 06/99 onwards at C connector pins 1 and 2, brown/red and brown wires.

    Since this seems to be a car with a CAN-bus based head unit, the illumination wire should not exist on the A-connector, neither the speed signal but the new unit may not need that. It is a bit odd to me if it did have constant power wired to the A-connector from factory but since Shude says, this may or may not exist, I guess it just did on this car even if the factory HU would not have needed it.

    Attached the pin assignment for a W203 Audio 10. You can see that the wire colours are not all the same (I thought the constant power should have been red with a blue stripe but still different, like some other wires).
     
    Last edited: Jan 18, 2009
  13. OP
    OP
    DSLiverpool

    DSLiverpool Hardcore MB Enthusiast

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    well the orange is taped up and the brown pair left well alone, the Sony autodims and knows when the iggy is switched plus the leccy aerial perates when tuner is selected (smart) - ONLY connections are the two din plugs - nowt else.
     
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