So, I had the good fortune of driving my S85 for almost two weeks in random Prius (limp) mode. Here's what I discovered:
- the fault code switched sides when I swapped throttle actuators from bank 1 to bank 2. This verified I had a faulty actuator and not a position sensor.
-Rotating the gears to realign the bad teeth in the throttle actuator had no effect. It still faulted.
- having a good daily commute to monitor when it dropped to limp mode, it normally occurs when the throttle actuator would have been shut and the idle actuator open. Interestingly, the fully shut throttle body position has the throttle actuator arm at the twelve o'clock position. This aligns the bad teeth on the black gear with the white gear.
The gears appear to be common between the S65 and S85 throttle actuators. I am working with another guy overseas to design and make an improved set of gears or them. Will update here if it does any good.