Having had the gearbox to bits (well – in a few bits) i want to be sure all the gearbox electrics are all working ok before it goes back in the car. There is a switch for the reversing lights and a switch for the overdrive both fed by an aging wiring loom. Had to refer to the wiring diagram to identify which of the 3 wires did what. The white/red stripe feeds the overdrive switch which after activating the overdrive solenoid goes to earth. The reversing switch is an on/off for the two green wires.
I used a multimeter and all was ok but a wire, battery and bulb would also do the same job.