The tailgate of my 2000 2.8 A6 Quatro wagon recently stopped locking. it makes a noise when I unlock the other doors, but it just won't engage. Locking the other doors does not arm the security system either. This is my first difficulty with the locking system or the tailgate.

I removed the lower tailgate liner, and I see there what appear to be two actuators one of which is a part of the core lock mechanism. I also see the device that engages a lug on the sill. Linkages on these parts connect them to one another as shown in the Bently book.

It would be very much appreciated if some could suggest how to test these parts or what the difficulty may be. Thanks, RKHick