I’ve read many topics on door lock problems on this forum, but haven’t seen one exactly like mine, at least that I’ve recognized. My issue is with a 1992 XJ6 vanden plas, 75,000 miles. I recently acquired the vehicle and discovered the door locks, trunk, and gas cover will not unlock using the mechanical key in either the driver side or passenger side key switch (there is not a keyless entry system installed). The key will lock all of the locks (plus trunk) when used in either door, but sadly, won’t unlock a thing from the external door locks. The doors and trunk will all unlock when the drivers side or passenger side button is pulled up. They will also all lock when either button is pushed down. The mechanical key will lock and unlock the glove box and the trunk, and works in the ignition switch.
I suspect mechanical linkage to be the culprit, but I find it odd that both door locks would have this same problem at the same time. Before I remove door panels, anyone have any thoughts?