By looking at my datalogs in detail I've discovered my PCM is not getting a signal as to when brakes are applied; logs show that brakes are never applied.

What does this affect in the tune, if anything? Does it trigger or change any modes such as decel enlean? Control the TCC? I don't notice any ill effects drivability-wise, but decel is very rich and difficult to tune in that area.

I have not done any diagnostics yet as to why there's no brake signal. But I have a hunch that it's the pedal switch. I had some problems with it several years ago where one of the two connections seemed to be going bad. But brake lights worked and cruise control was inop then (and still is) for other reasons so I didn't worry about it. I'm guessing now I'll need to worry about it. (If nothing else, I do plan to get CC working again so I'll at least need it for that) From what I can tell, there should be a single purple wire coming from the switch to the PCM?