First time swap started

[AussieinNC]

Originally Posted by skyphix

Very likely, and the proper brake switch. Mine was originally a manual transmission so I've had to add the proper brake switch.

With my 4L80E, the TC locks up, but doesn't unlock appropriately when the brake is pressed so it pushes VERY hard until the truck is basically stopped completely, when the PCM Finally unlocks the TC.

There are several settings within the PCM to reset the speed points of the TC lockup/Unlock.

Your description of "pushes very hard" tends to indicate the Unlock setting is way too low....

HP tuners and other aftermarket programming systems have this capability.