I interpret the description above as the sensor check was performed without having the engine running, just ignition on. Is that correct? I volunteer to ask stupid questions. It will be quite clear to most of you that I'm not an engineer. If there is a sensor that delivers different voltages for each gear position why then is an altered final drive messing up things for the ECU and gear indicator? Couldn't the gear indicator be satisfied with these different voltages and just not bother about rpm and road speed?