I want lights to extinguish when tailgate is closed.

[M80]

Viano 639, 2014.
The rear wiper doesn't work when the tailgate is up.
So the SAM recognises it being closed.
That though is 'likely' to be a canbus signal, from within the lock mechanism is my guess.

But can anyone suggest a way to pick up a changing state terminal that I could use for a relay perhaps?

 

[supernoodle]

CAN is just a means of communication. Even if there a CAN signal for open/closed status there would have to a physical hardwired signal read by a module for that to be possible.

Is there a switch in the lock mechanism? If so I would expect it's make/break set up. You should be able to suss it out with a multimeter.

 

[M80]

Is there a switch in the lock mechanism? If so I would expect it's make/break set up. You should be able to suss it out with a multimeter.

In the sliding doors there is a micro switch that recognises the door as closed.
I'm assuming the same for the tailgate.

My thinking is that to try and utilize that for such as a relay might confuse the 'calibration' of the signal to the SAM, via the canbus??