Thrustmaster Hotas RJ12 Rudder Connector

I'm running X-Plane 11 with a Thrustmaster Hotas joystick and Propedals Rudder/Brakes. So I have theoretically 3 extra analog axes available at the rear RJ12 connector on the joystick where the Thrustmaster pedals would usually plug in and I would like to use these for trim, propeller and mixture inputs.

So I made a personalized RJ12 plug by taking a standard RJ12 plug, filing it down and adding some epoxy so it fits nicely. (For those of you that don't know, the Thrustmaster version of an RJ12 connector has an offset fixing lock.) So I was able to bring out the 6 wires. Measuring the voltages and checking the impedances there seems to be Vcc at a reduced level of just under 3 volts, a ground wire and 4 high impedance input wires. I hooked up some 100K pots between Vcc and ground with the sliders going to the input wires. This all seems logical yet when I go into the calibration screen nothing I do will make the pedals axes move.

As there are 4 input pins and only 3 functions I suspect that something very simple needs to be done to one of the 4 input pins to tell the joystick that the pedals are present.

 

Does anyone have the schematic of the Thrustmaster pedals with the RJ12 connector or know the pin assignments?

Or have any suggestions?

Thanks

 

PS Before anyone asks the Control Panel Properties is set to 5/8 axis mode so it should be a hardware issue and not SW.

Just an update as I did work out the solution. As there were obviously 4 input pins for 3 functions I decided that one of these must be a sensing pin to activate the external functions. This turned out to be true. The pin sitting at about 3V is the sensing pin and when you ground this pin the other 3 input pins are activated as well as the real VCC pin. Connecting these pins to sliders of 100K potentiometers with the ends wired to VCC and 0V gave me 3 functional inputs. Two of these I used for aileron and rudder trims and the 3rd either as mixture when flying piston or reverse if flying jet.