PCM of NC 4L60E to 4l80E Conversion Harness. P-120021, 1999 to 2008
This harness makes a 4L80e conversion MUCH simpler – plug and play! Max out one parameter, retune for your new shift points and you’re on your way! No complicated OS swaps or hurdles to jump. Cruise control and gear shift indicators work just as they did in stock form! Converts any 4L60e, 4L65e, or 4L70e to 4l80e. NOTE: 2009+ four speed transmissions use an Internal Mode Switch instead of the standard side-mount park/neutral switch. This switch will be needed to use our harness. Tested in Travis Wester’s GTO to a record 8.74 @ 156.71mph in the quarter mile!