From my other post..
I've had a few people contact me to ask how to wire up the tailgate lock, so here's how.
Why it's different
The barn doors uses a mechanical lock similar to the front doors. When you unlock the van, the body control module (BCM) sends power to all the locks for a fraction of a second which moves a solenoid in the locks to unlock them.
The tailgate uses electrical switched on the outside and inside of the tailgate, and sometimes one in the front door to tell the BCM to open the tailgate lock. Even though these switches are pressed, the BCM will only open the tailgate if the van isn't moving and the doors are unlocked.
How do you do it?
The wire telling the lock to unlock on the barn doors can't be used and needs to be cut and taped up. This wires does go back to the BCM but is still needed to unlock the front doors so don't change this wire on the BCM.
You need to add 2 wires to the tailgate connector from the BCM, one for the switches, and one for the lock.
Connections.
The tailgate has it's own harness with a 17pin connector joining it to the van.
1 - LOCK - From Pin14 on the tailgate 17pin connector to Pin10 on the black plug of the BCM.
2 - Switch - From Pin13 on the tailgate 17pin connector to Pin23 on the black plug of the BCM. (If you want any additional switches to open the tailgate, just add another switch in parallel earthing Pin23 from the BCM)
3 - The tailgate needs an earth. Pin 15 needs connecting to the earth point down the D-Pillar near the rear light.
Coding
Now you need to tell the BCM that a tailgate is fitted and it needs to look for the switch signal.
Using VCDS, go to Module 9 Central Electrics and enable these.
Byte 01 Bit 5 Central Locking/Rear Lid: Contact controlled on detent
Byte 01 Bit 7 Central Locking/Rear Lid: Rear Lid Locking/Unlocking via Central Locking
Byte 07 Bit 5 Central Locking/Rear Lid: One-Motor-Lock installed
(This is from memory, hopefully someone can check it)
Testing
Hopefully at this point your tailgate is working correctly.
To test the lock, you can manually trigger it using VCDS.
VCDS monitors if the latch is fully engaged or not. Select Measuring Blocks Group 006:
Field 2, field 3 = "Open", "Open" = when rear lid fully openField 2, field 3 = "Closed", "Open" = when rear lid ajar (at first latch).In the picture below the lid was obviously closed.
To check if the BCM is
getting the signal to open the lock, the statu
s shown in Group 008, field 4. Just indicates that the switch is pressed or not.
