This thread has a diagram of a typical circuit for steering wheel controls.
Steering Wheel Interface for Pioneer Radios
Though it is for a Pioneer radio and uses different resistor values the diagram is similar to what is found on a Mirage / Space Star circuit. If you are able to read a schematic diagram it will be useful to you.
I hope this helps you. Best wishes.
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View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)