It's a purple cable and it's probably hiding on either side of the cut out. You may need to make yourself a little fish wire with a hook and see if you reach in and snag it.
46 Years RVing and no end in sight.
2018 Ram 3500 SB Limited, CC, 6.7/Aisin, 4X4, SRW. Comfort Ride Energy Absorbing Hitch.
2020 Cedar Creek Hathaway 34IK, Reese 19K Sidewinder PB.