Wiring is very simple if you go with Kufatec loom:
KUFATEC
For VW T6 Multivan Bus etc. Genuine Kufatec Cable Loom Electric Tailgate 4251194896122 | eBay
Everything is plug and play and all you need to do is the following:
- connect permanent power supply, plus 12V DC via 30A fuse and minus anywhere to the chassis.
- CAN L and CAN H wires to BCM convenience CAN bus(orange/green & orange/brown).
NOTE: Electric tailgate won't work with power-train CAN bus(used for LED lights range adjustment, parking, etc.)
- driver door switch: 3 wires(minus locally inside door, illumination directly from BCM & opening/closing signal to BCM)
There is no wiring for parking system by Kufatec as electric tailgate can be retrofitted to T5FL & T6 with no parking sensors.
The only disadvantage of non parking sensors setup is no protection for obstruction detection during remote opening. Tailgate will open remotely but without any detection for obstruction(obvious!).
But if you do have parking sensors you can easily add on that functionality, cause electric tailgate control module produces dedicated 12V DC output which engages a relay(typical automotive will do) which then powers up parking sensor control module. All communications including permission for remote opening goes via CAN bus.
And finally tailgate power latching is also to be done if you don't have it already onboard.