No announcement yet.

Tutorial: Maestro/Montego audio-loom to ISO

  • Filter
  • Time
  • Show
Clear All
new posts

  • Tutorial: Maestro/Montego audio-loom to ISO

    This applies to cars from around 86/87, which originally came with three separate connections for the Philips radio cassette players:

    A long connector with a purple, a green and a black wire in it. This is for power.
    Two pairs of DIN speaker plugs, one black, one white. These are for the front and rear speakers respectively.

    If the connectors are still in place but you want to use a modern ICE unit with ISO sockets, rather than chop off the connectors it is much safer and tidier to use a commercially-available converter, such as this.

    However if a PO has already lopped off the original connectors, this tutorial explains how to ‘map’ the Austin Rover audio loom to a modern ISO loom.


    Permanent Live: Car – Purple. ISO – Yellow
    Switched Live: Car – Green. ISO – Red
    Ground: Car – Black. ISO – Black


    NB: The speaker wires are grouped in coloured pairs. On the car’s loom, one wire in each pair has a pink/peach tracer and the other wire has a black tracer. On the ISO plug’s loom, one wire has a black tracer and the other wire has no tracer. When connecting the car’s wires up to the ISO loom, match the wires with the black tracer together to keep the speakers in phase with each other.

    Front Left: Car – Yellow. ISO – White
    Front Right: Car – Orange. ISO – Grey
    Rear Left: Car – Blue. ISO – Green
    Rear Right: Car – Grey. ISO – Purple
    Last edited by G51 NAV; 30th October 2009, 19:16. Reason: Clarification.
    John Orrell

    MG Maestro Turbos 396 and 502
    MG ZT190+ (53 plate)

  • #2
    Also applies to ledbury built cars too.

    A couple of points to add:
    On many modern stereos the red and yellow wire are reversed. This is because some car manufacturers didn't strictly follow the ISO code. Most modern aftermarket stereos have connections you can alter on the radio loom as it is such a common problem. It won't damage anything if it is the wrong way round however if your stereo loses all its preset stations etc when you turn the igntion off then suspect this as a potential problem. Ditto if when you turn the volume up loud the fuse blows (switched live is a bigger fuse than the permenant live).

    Also dependant on stereo you may need to add the radio illumination wire (red/black on the maestro). This will either illuminate the radio when the side lights are on or dim the display brightness for modern radios. - The Tickford Maestro Turbo Register - The Rover 200/400 (R8) Owners Club - My Rover Diesel Site


    • #3
      Wire in the ISO loom as it should be fitted, and then if the battery back-up and supply feeds need to be swapped round to suit the stereo then a conversion lead can be purchased (designed I think for Vauxhall/Saab cars). That is what I did when I re-wired my maestro for ISO connectors.
      Certain stereos (Like my VDO Dayton one) have the facility whereby they are switched on as normal using ignition position I, but can also be turned on independent of the ignition. That's why the swap-round situation arises.
      M&MOC Committee Member - Archivist
      Join the M&MOC | Visit the Club Shop | Printable Club Flyer (PDF)


      • #4
        Just a quick update on this to mention an important point: if you're going to chop-up the purple and green wires (ie the power supplies), do disconnect the battery first so that there are no accidental shorts which either blow a fuse or worse still cause a fire.
        Last edited by G51 NAV; 23rd July 2011, 19:33.
        John Orrell

        MG Maestro Turbos 396 and 502
        MG ZT190+ (53 plate)