rear assist module
 

i bought a 2011 chevy traverse with slight rearend damage. evertthing is fixed now except i keep getting service assist on dic. i changed all 4 sensors and put a new wiring harness for the sensors. i can see the module in the left rear quarter area where the jack goes but cant figure out how to remove the bracked the module is bolted to. it looks like its bolted from the inside. lastnight we removed back bumper to replace wiring harness thinking i could get to the module with the bumper removed but there is no way.please someone help.

park assist
 

so i figured out how to change the module but still getting service park assist. i changed all sensors the wiring harness and now the module.what else can it be?