Doors unlock themselves?

Hello, Forum. I've lurked here and on other sites for a few days, and concluded this is the best Jaguar Forum on the net. I am considering buying my friend's XJ6 (my first Jag), and hope you can help me navigate the quirks and peccadilloes that, I understand, come as the price to pay for the Grace, Space and Pace offered by this magificent machine.

Let's start with the door locks (FYI: The remote is lost).

I've been driving this 95 XJ6 for about a week. All was well until yesterday when my fiance ran some errands and came back to tell me the doors no longer lock.

Upon inspection and testing, I found the driver's door key rotated to stop in both directions as normal (although I don't feel the subtle resistance turning forward I felt before), but does not move the lock.

The passenger lock mechanism works to open the door, but as I go to lock it, the plungers go down, then come back up again, and the double *beep* of the alarm is joined by a louder *chirp* as the plungers rise (I assume this is telling me the alarm is armed, but the doors are unlocked). Also, when I put the car in gear, R or D, the dome light comes on, then fades out like I just shut the door.

Is the computer (CPU?) telling me it's getting crossed signals from the doors, or does it think one of the doors is still open (bad sensor)?
I don't have any service or owner manuels, and my normal databases don't cover Jags. Where do I start the diagnostic?

Does anyone here recognize the symptoms? If not, what other info do you need?

 

My brief oddity with mine.

The key not firming up as you rotate is not a good sign. It means that the plastic link on the lock inside the door is either broken, or fell off. Mine also came with no fobs, so i purchased a universal remote door locking kit for $69, and used the interface and fobs only. The interface is mounted inside the drivers door, and the wires in the loom were spliced to provide the volt drop signal required to trigger the factory system. A bit of fiddling, and drinking, but it works sweet.

Each actual door lock has a MINI micro switch for the interior light, and possibly it also has some signal to the rest of the system that the doors are closed, so do your thing. If that/those switches are flaky (and they do go that way) the system does not recognise that the door is closed, so arming is going to happen. Why the plunger rises again, DUNNO.

 

Hi JFerg,

Yes, this is a good forum. A nice community of people who appreciate the finer things! And dont mind spending time and money on them!

The door locks all pop back up whilst using the right key lock because... The left button wont go down to the locked position. Hence the alarm refusing to set (with loud beep). All doors (and trunk) must be closed and with button down to lock and arm. Looks like job one is to take apart that left door. Bummer.

The door locks and alarm systems on these cars can be tricky. I am blessed to have three that work properly. I spent my time setting them straight. Im sure youll find lots of help here.

A small $20 investment in the factory service manuals on cd is the best money youll spend on the car!

 

Of course! It makes sense now. Thank you, gentlemen, for your quick response. I'll open her up when I get some daylight and look around. I saw a thread that mentioned the lock mechanism's penchant for throwing the linkage you mentioned, and they recommended using zip-ties to secure it. I'll let you know what happens.