2007 Pontiac Grand Prix GT

Engine Size : 3.8
Question: When i put the car in drive the door locks won't apply and the inter lights stay on, if i put the car in and out of drive the locks will apply sometimes there must be a switch on the drive trans where is it and what is it called ?

Answer: The automatic locking and the interior lights are controlled by the Body Control Module(BCM). This module gets its input from the park neutral range switch to know what gear the transmission is in. I would suspect a problem in that computer. Getting a scan of codes may help. This could also be a problem in the park neutral swtich, but that would usually affect the ability to start the car in park or in gear. You could test this by making sure the reverse lights come on when you shift into reverse. If not, it may be out of adjustment or needs to be replaced.