locking issue

[hamburgler]

hi there, new here.

i have a locking issue. i do not have the fob anymore and the dealership wants too much to replace it so i have been using my key. when i unlock the front driver door the rear drivers door will lock and when i lock the drivers door the rear one will unlock. i have also noticed that if i have the rear passenger door open and i push down the lock it will unlock the truck and when i unlock the rear passenger door it will lock the trunk. i have a 2002 xc70. where to start troubleshooting?

[howardc64]

There is a lock position sensor inside each of the 5 door locks (4 doors + hatch). When one of these is bad, the sensor reports the wrong locking status and the central lock software won't work properly. When I had this problem, locking the door from driver door module is fine but unlock doesn't work (I vaguely recall it unlocks and then locks again right away). Key FOB still work correctly so it must have a different path. This is a fairly common problem.

You will have a code stored (but no check engine light) Just pull the code and it will tell you which door lock is bad. If you connect Volvo's diag tool (VIDA/DiCE), you can actually see this lock sensor in all 5 doors and see the bad sensor report the wrong status as you push the driver door module's lock/unlock button.

The door lock module is fairly pricey. I think $150-$200. Volvo list several models for this lock so make sure you get the right one. Here is a picture of my right rear door lock. I replaced it due to a similar issue.

https://picasaweb.google.com/howardc64/DoorLocks