Ok, so I got to the industrial area and drove around and around, first in Auto mode. After the earlier whopper 1st gear episode, didn't have any further problems. That said, about all of my testing occurred in a straight line, as the Steering Angle possibility hadn't yet occurred to me.
Then did a stint in TipTronic mode, and again, no issues.
Since it was a warm day and things were getting hot, thought I'd test that out a bit too. Spent time stopped idling to increase temps until I got tired of it.
Got the ECT (Engine Coolant) Temp up to 95°C but the fan didn't cut in. Not sure what temp that's supposed to happen, but that's when I noticed that the good old analog (stepper motor driven) temperature gauge is BS. Even at 95°C (in FORScan), the needle was sitting at 79 on the dial. Don't know what use that is.
Got the TFT (Trans Fluid) Temp up to 92°C. There was no warning or DTC or anything else, though the
TCM's behaviour may have changed a little. It's supposed to do something to reduce the temperature in these situations. Evidently, the earlier link about 82°C being hot for the TFT in an S-Max doesn't apply here.
Anyway, even at these temps, I didn't have any further bad transmission behaviour.
Also took at look at the TF cooling circuit. It runs from the External Filter Housing (Base) through the heat exchanger that's bolted to the Radiator and back to the filter housing.
The Coolant circuit through this heat exchanger appears to be in parallel with the radiator, which basically means that once the TF temperature is high enough (for the
TCM to enable the cooling circuit), the Trans Fluid Temp is tied to the Engine Coolant Temp, all regulated by the Engine Thermostat.
Also checked out the trans fluid pipes for temperature difference simply by touch and figured that one pipe is somewhat hotter than the other, suggesting there is fluid flow through the heat exchanger.
Will dig into the Steering Sensor thing...