Car Stereos: Dual XD1222 stero wiring for Miata 96, wire nuts, wire colors

Question
First do I need to buy a separate wiring harness to go from Mazda's harness to the dual xd harness??
If not what Mazda wire color correlates to what dual xd 1222 wire color??

Answer
Hi Dan,

Sorry about the delay in answering this question.  If your factory radio plug is still intact in the Miata, then I'd definitely recommend buying a wire harness adapter to install the new head unit.  The Miata takes a standard Mazda wiring harness; the Metra part number is 70-7901.  

You'll need to splice the wire harness to the wiring plug that came with your Dual head unit; the wire colors should match up, so you just have to connect the wires using solder or solderless crimp connectors.  Don't just twist and tape the wires, and don't use wire nuts--these aren't reliable connection methods for vehicle wiring.  If you do use electrical tape, be sure to use good quality tape like 3M's Super33+.  Cheap electrical tape will turn brittle and fall off after a time.

There will probably be a few wires on the adapter harness that don't match any wires in the Dual plug; just be sure to insulate these wires and don't connect them to anything.

Hope this helps!

Brian