Update: I'll make this short:
* bought 2015 with 70k miles, no CDL light on that I ever saw
* took into service at lexus dealer, got all diff and transfer case fluids flushed (and more)
* Maybe 30 miles after that, CDL light flashed when starting lexus. eventually went off after multiple restarts
* Later that day (just now) - I took the LX570 out to a gravel lot, and exercised the CDL. It took a long time (5 minutes?) to get it to finally engage - but once it did, it engaged faster on subsequent activations and de-activations. seems to be pretty quick now.
Question: for the 200 series, at this point, the CDL normally engages within a few seconds, sometimes longer, sometimes as much as 30 seconds or so. Similar for disengagement. And it normally doesn't make much sound but sometimes it thunks/clunks pretty heavily when turning the center diff lock on or off. My experience in Tacomas and 80 series is that this is pretty normal - is that what people experience on the 200 series in general? It doesn't always engage right away, and it clunks sometimes?