Central locking tailgate fails, remote works erratically

[Franz47]

850 TDI station wagon 1997 automatic lhd 200000 miles done (TDI never sold in the US but doors surely the same as in gasoline models). Central locking mechanically and by remote control has worked for years. Since several months I have problems. Though several similar problems have been posted here and solutions proposed I am not sure with my problem where to start.

The symptoms:
1. Central locking never locks/unlocks the tailgate lock any more.
2. Key in both front doors locks and unlocks the 4 passenger door locks
3. Button in both front doors inside locks the 4 passenger door locks.
4. Opening inside handle in both front doors unlocks the 4 passenger door locks
5. Key in tailgate lock locks and unlocks the 4 passenger door locks and mechanically locks/unlocks tailgate lock.
6. Remote control always causes 1 blink of all orange lights regardless of mechanical events in locks and regardless of position of locks (locked/unlocked)
7. Often remote control locks the 4 passenger doors, but then suddenly it does not cause any effect except blinking light.
8. Remote control never opens any door, just blinking lights.
9. When listening inside the car and pressing the remote control button I can hear a click in the left frontside under the dashboard where the relay is situated and a click which seems to come from somewhere in the right front door (??) though the receiver should be under the dashboard to the right of the glovebox.

If there was not the erratically locking by remote control I would at first point at the actuator motor in the tailgate lock. But so I am really puzzled. Relay? Very difficult to get at with normal size hands. Remote control receiver?

Any best guess for my problem?

Franz47

[BEJinFbk]

Have a look at the wiring harness where it passes from the car to the tailgate.
Sounds like you may discover some damaged wires back there. It happens.

[Franz47]

[quote="BEJinFbk"]Have a look at the wiring harness where it passes from the car to the tailgate.
Sounds like you may discover some damaged wires back there. It happens.[/quote]

I know about this possible problem and I hope that this is not the culprit. But how would a broken wire to the tailgate lock cause erratic effect of the remote control on unlocking passenger doors? And can a broken wire there cause that the remote control causes the lights to blink but cannot open the passenger doors´ locks?

Yesterday I tried to remove the inne panel of the tailgate according to the instructions in the VADIS but gave up after a while because I was afraid I would break something.

The side piece around the door opener should be handled like this: "Remove the trim around the door handle by inserting a putty knife in the tip of the trim and prising it downwards." The side piece would not move a single millimeter and I hesitated to break it.

The panel should be removed like this:
" Remove the lower panle by grasping between the rubber strip and panel with your fingers and pulling the panel back and down to release the clips. Undo the entire lower edge of the panel." etc etc
Again I stopped pulling because the panel would not move and I was afraid to tear it apart.

Any advice on that?

I thought I might check whether there is voltage arriving at the actuator when operating the remote control at first and whether there is a broken soldering point inside it if voltage is present but not causing the actuator motor to work. If I would not find any voltage arriving there the next would be the cables in the hinge area.