Right, I have swapped the two wires around and its now reading the correct way. However, at idle the voltage is reading 0 volts, i need to apply a tiny bit of throttle pedal to get it to read 4.6v and then it decreases nicely to around 0.35v at WOT. Does this mean I have to adjust the TPS physically to get it to read 4.6v without depressing the pedal??

So close yet so far