Ah, it's using that instead of the more normal temperature sensor on the reducer.
Once the sensors tell the ECU that conditions are right to change over (reducer temperature and gas pressure), it doesn't just change but it looks for a change in revs. It is usual on a multipoint to set it to change on acceleration as the revs pass a certain point. You want it to switch over at fairly low revs, my SE was set to change over at 2,000 rpm so, in theory, it should have changed over as you accelerated past 2,000 rpm. But if you were driving normally in traffic, it would never reach 2,000 rpm as the gearbox would change up before the revs got that high. I could drive for miles with the ready to change light on the switch flashing and it would only change if I dropped it into neutral and gave it some revs. So, you want it to change over at an rpm setting that you will achieve normally, 1,300 rpm would probably be a good one to try.