Sliding

Hi, My 2014 Vrs Combi is making a noise for about 5 seconds after the tailgate has closed. The noise sounds like the gears are slipping inside the motor. Im guessing it has not recognized the tailgate has closed and keeps trying to close it. A VCDS scan shows 0128 Closing assistance closed B113e F1 (008) Implausible signal. Where is the switch located that tells the control module the tailgate is shut? I tried putting a screwdriver in the tailgate latch as it was closing to simulate it hitting the latch pin. The tailgate stopped closing straight away and there was no noise. So Im picking the switch in the latch is okay. Anybody have any ideas on where to look? Thanks