Rear (Trunk) Door Does Not Lock

[Oka]

When the car is locked (key or remotely), I can her the mechanism of the whole system but when I check the rear door, it won’t be locked. Got the car in March and installed a remote in April and can’t remember if the issue has been like that before or after the remote installation.

How can I check what the issue might be?
Thanks.

[guyeye]

Does the rear hatch lock move or make any noise whatsoever? If so, the problem is probably in the lock mechanism itself (jammed, worn, corroded, etc.). You may be able to free it up. If no sound or movement from that lock is detected, it may be that danged wire harness that pinches and causes so much grief. You could try putting an electrical tester on the lock mech. and activate the lock. Either way, you will have to remove the back hatch interior panel (see resorces).
If it's a control fault, a dice scan should tell you.
I don't have any first hand experience with this, but I think I've covered all the troubleshooting bases. Anyone else?

[guyeye]

Does your remote have that weird trunk button (that I never use)? If so, what happens when you just press that (twice)?

[swimNdrive]

When the car is locked (key or remotely), I can her the mechanism of the whole system but when I check the rear door, it won’t be locked. Got the car in March and installed a remote in April and can’t remember if the issue has been like that before or after the remote installation.

How can I check what the issue might be?
Thanks.

I had similar problem before. It was the wiring problem. In your case, you may want to check the wire near the drive side hinge and trace it all the way to the lock. And on the other end trace to the connector in the rear speaker housing inside of D pillar. It could be more but these are the area I would take a first look. There are some threads on XC70 tailgate problems and DIY repairs. Google it you will see them. They are very helpful.

[Oka]

. . . you may want to check the wire near the drive side hinge and trace it all the way to the lock.
Could you please be a little more specific, sure there should be lots of wires in that vicinity? Any in particular I should be looking for?


Does your remote have that weird trunk button (that I never use)? If so, what happens when you just press that (twice)?
Nope! My fob does not have the trunk button - just Lock, Unlock, Alarm and remote start (the latter being why we really need it in our cold region).


Does the rear hatch lock move or make any noise whatsoever? If so, the problem is probably in the lock mechanism itself (jammed, worn, corroded, etc.). You may be able to free it up. If no sound or movement from that lock is detected, it may be that danged wire harness that pinches and causes so much grief. You could try putting an electrical tester on the lock mech. and activate the lock. Either way, you will have to remove the back hatch interior panel (see resorces).
If it's a control fault, a dice scan should tell you.
I don't have any first hand experience with this, but I think I've covered all the troubleshooting bases. Anyone else?
No, the tailgate door mechanism does not seem to be moving with either key or remote.
Using the electric tester is an easy task but where to contact witht he tester would be the issue.
My DICE did not show any issue that I could read (comprehend). I will connect the DICE latter and post anything that might look like it is related to the locking mechanism.

Tomorrow, I would have to open the tailgate cover to snoop in there.
Thanks you all for all the information.

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UPDATE:
Could not wait so I went and opened the tailgate cover, locked and unlocked the system with both the remote FOB and the key.
On both times, the action stops at the module in the trunk, on the driver's side with the fuses, relays and electrial units.
With either opener, I can here a click like a relay is functionion. However, no mechanical part moves in the tail gate's locking assembly.
All the wires seem to be sitting well, so what next?

Thanks.

UPDATE #2
Found the culprit! Fuses! In the trunk, driver's side!
From lots of post I read on line, first I tried to move relays around then decided to do what I should have tried first,
check the fuse(s). I found out fuse #6 for the tailgate was burnt I took one from #1 put it in #6, tested the door lock,
and it won't work then I realized that was got burnt also. Then I replaced bot fuses and wll works well (for now).
Really amazing to feel safer again. Sure was an easy fix except the time it took me to find the issue out.
If anything should change, I will report again.

Thanks for all the help here.

UPDATE #3
Well, just realized everything locks except the gas tank lid. What's up with the lock?
Thanks.