disconnect the battery and force it to relearn.
Yeah, disconnect for an hour to make sure it clears the tranny computer.
However, to disconnect the battery, be sure it's 15 minutes after the key was taken
out of the ignition. There's GMs "RAP" "retained accessory power" if you disconnect within
15 minutes, the computers kick in a one-use Lithium primary battery associated with OnStar
system and drains it flat.
disconnect the battery cleanly, keep good contact while undoing clamp, then pull off in
one clean move or computers will interpret rapid electrical make-n-break of the ground wire
as an accident and kick in the lithium battery above. Same applies when you re-connect,
do it in one clean move without multiple make-n-break moves.
GM doesn't want you to know, they'd like to fix your OnStar!!