[monkeh]

Originally Posted by bananarama

I assume I would to reset the TCM because if I pump out most of the ATF in one go, the ATF quality has undergone a drastic change, and the TCM needs to know about this?

I doubt it, you're only removing about a quarter of what's in the system if you are lucky. You've got fluid tied up in the TC, clutches, valve bodies, cooler etc.

There'll be a good few litres in the converter. Given my experiences doing a partial fluid change several times in that manner, I'm sure the TCM would realise that the fluid is changing slightly and adapt itself.