Well, it's a long and kinda painful story, but here goes since you
asked! My Caravan was struck by lightening and it knocked out the radio
(just the AM band, oddly), the back up lights, the ability to control
the temperature, the two zone (driver/passenger) feature and the blend
doors (defrost, vent, floor)

I was able to diagnose the back up lights. The BCM was the culprit there
and I replaced it only to find that my OBD tool wouldn't read codes or
clear them like it used to and it added a code about a major and minor
exhaust leak as well as O2 sensor faults as soon as I installed the new
BCM. I then decided to ask a friend to replace the tiny chip that was at
fault for the backup lights in the old unit with the same one from the
"new" BCM(the damage to it was quite apparent) and he did so
successfully. The backup lights then worked but I retained the new fault
codes and was still not able to navigate the OBD system as I used to.

I have taken apart the motors that control the blend doors and they
respond well to a 9 volt battery--they all operate both directions
depending on the polarity provided. The doors themselves can be
manipulated by hand.

When I do the calibration test now (at 25ish degrees) the recirc button
merely flashes after the other lights go out. Don't know if that is
because it is too cold to do the test or if the flashes are a code
(although they are very regular and go on forever...)

There, how's that for too much information?

Thanks,

Allen