My 2005 XK8 convertible (RHD UK spec) has suddenly developed a problem with the alarm sounding when the car is locked. The symptoms are:
If I lock the car using the remote or the key the drivers door handle cycles several times and the alarm sounds. The passenger door remains unlocked.
With the passenger door manually selected locked from inside the drivers door cycles 5 times and locks. If the drivers door is now manually unlocked from inside the handle cycles (x5) and unlocks. Passenger remains locked.
The car can now be locked with the remote - no alarm.
Pressing unlock on the remote the drivers handle cycles and unlocks - no alarm. Passenger door remains locked.
Still with the passenger door locked, locking with the key is OK but unlocking with the key sounds the alarm, however unlocking with the remote is OK - no alarm.
From inside the car the passenger handle will lock and unlock both doors - no alarm.
Moving the drivers handle to lock or unlock cycles the handle (x 5) and stays locked or unlocked. No effect on the passenger door handle.
During drive away drivers door locks passenger doesn't.
Windows and internal lights work correctly.
Battery is normally on a trickle charger and is well charged.

Any suggestions gratefully received.

 

Mike, the times this happened to me it was a sure sign of a low battery. Do you own a charger? Hope it's that simple mate.

John

 

Hi Mike,
Two unrelated items. The alarm will always sound if you use the key to unlock (mine does, and I don't think that changed on the later cars), although you should get a series of warning beeps and about 7 seconds or so to get the key in and the ignition turned on.

If you're sure the battery state is fine as John suggests, then it's likely one of the door latch mechanism microswitches is playing up.

 

I doubt that the battery is at fault. I have a very good charger which is connected when the car is not in use. But thanks for the hint anyway.

 

Hi Mike,
Thanks for your input - unlocking with the key I get an immediate alarm, and no warning beeps. Silenced only by pressing the unlock on the remote fob.
The battery is kept charged on a CTEK MXS 5.0 charger when not being used for a few days so I am fairly sure of it.
Do you think the problem could stem from a faulty Door Control Module, if so which one?
Regards

 

From what you describe it’s probably the door latch itself which has microswitches that are known to go bad. Spraying WD40 through the gaps into the latch may buy you a few weeks but eventually it seems to come back.

Removing the latch from within the door is relatively straightforward and you can DIY replace the microswitches. Lots of forum members have gone through this.

Small hands makes the job easier.

Let us know how you want to proceed.

 

OK so the alarm issue may be related inasmuch as it's a symptom (but not a cause) if it fires off immediately.

I can find many posts on this topic, but no definitive answer. I would lean towards the door latch mechanism itself, and associated microswitches rather than the door control module at this stage, although I've not yet had the pleasure of troubleshooting this fairly common issue.

Other suggestions are to disconnect the door harness plug and use some contact cleaner on the connectors, and to try a hard reset. Worth a try as they're both $0 checks.

Member Gus has some information on the door latch mechanism on his site here:
JagRepair.com - Jaguar Repair Information Resource
Hard reset:
JagRepair.com - Jaguar Repair Information Resource

Other hits were
dnarraf:
https://www.jaguarforums.com/forum/x...7/#post1478270

Andy ***:
https://www.jaguarforums.com/forum/x...92/#post790450

gordocatcar:
https://www.jaguarforums.com/forum/x...9/#post1456122

and one from the Other Place by DanW:
https://www.jaguarforum.com/showthre...l=1#post539980

 

Hi David, having searched this and other forums your comment on the WD40 treatment is stated frequently. As for the micro switches there are 3 but I can find only how to deal with one and that is the "door ajar" or "door open" switch. I don't have any door open warnings so I wonder if it is that particular switch at fault.

 

Mike198,

Check out worrasf's thread with excellent photos of the latch and explanation. This made the "How To" stickies threads - high praise indeed! Link below.

https://www.jaguarforums.com/forum/x...closed-234331/

Relatively straight forward for access and removal, particularly if you have small hands, with a Youtube video by Rev Sam aka sam1174. Note : There is one minor correction to Rev. Sam's method in removing the latch's drop link.


Let us know how you're proceeding.

 

Thank you Michael some very good stuff in your post.
However since my post I put the car on a 24 hour charge just to be sure of the battery and I have renewed the fob battery. Now the symptoms have changed somewhat.
With both doors unlocked or the passenger door manually locked the remote will not lock the door/ doors, however the indicators flash and I hear a clicking from both the door handle areas.
The key will lock the driver’s door but not the passenger door (if not manually locked).
The key will unlock the driver’s door but not the passenger door and I get the 7 second chimes and then the alarm unless the key in the ignition or the remote unlock Is pressed - as you previously said this is normal.
I no longer get the cycling of the door handles.
Thanks again.
Mike

 

Thanks for all the advice and suggestions. It turned out there were two problems. Firstly the door lock on the passenger side (RHD UK spec) was at fault. It took some time to source a replacement (why on earth did Jaguar stop supplying them?) but once installed the lock was good but the alarm fault was still present. It again took some time to track down the culprit - a broken wire in the harness between the boot/trunk lid and the body. Once that was fixed all is now good.
Thanks to all, especially michaelh and DavidYau.

 

Hi Mike, can you tell me the duff wire please

 

Hi Wag,
I can’t tell you exactly which wire was damaged as it was my local specialist that fixed it. I can tell you it was within the wire loom that runs from the car interior and is attached to the right hand hinge support of the boot/trunk lid. Not only did that fix the alarm fault but with the fix I was able to open the boot using the centre button - that had been inoperative since buying the car. Hope this helps in any way.
Mike