Our friend Simon is a genius and should take all credit.
Little did we know that voltage is only supplied to the solenoid when the lever is pulled. Testing each and every pin for continuity multimeter would also have been a failure because of the resistance on the circuit board.
12 volts need to be added which are active upon pulling the gear switch. The solenoid is then active and unlocks the lever.
A minimum of 12V (up to 28V) can be used on the solenoid. 5v supply for the integral backlight and gear down warning.
x/w Solenoid (12-28v)
p/r Integral backlight (5v)
s/t Gear down warning (5v)
l/a Gear down (connect to your I/O interface). There are multiple redundant gear down connections.