hey guys, had a similar problem with a near identical R40TT,

When plugging/slowing down with counter-throttle,

The truck would get jerky, and eventually throw a 2F code for regen, strangely enough, the speed limit would not be cut...

Anyhow,

Replaced the regen(q2) unit with a new one, as well as the rec2 diode that came with the kit,

I did as forktech418 suggested, connected the regen 3-pin connector to the power card, but the two main power leads, i left disconnected, and ran the first self-test,

I instantly got code 23, figured it was due to the the two power cables to the regen being disconnected,

Connected the two cables back on the regen, ran self-test again... still code 23!

So far I've looked over all the obvious stuff, but I am still getting code 23...

I tried hooking up the old regen(q2) unit again just now, just to check, and still have code 23...

Any input fellas?

Started with a code 2F (when plugging), and now I have a code 23 all the time...