I know the central locking issues have been posted on this forum to death and believe me when I say that I have gone through them in the hopes that I could resolve my issue without having to post it here, but alas, here I am. My 92 XJ40 has been driving well with the exception of a slight stumble on the idle when coming to a stop. For that, I will be cleaning out the throttle body, EGR and changing the IACV. No codes as of yet but that is not a big issue for me as of the moment.

The real issue i have is with the locks. All of my lock actuators work and have been working brilliantly until the other day when I hit the central locking button and the windows went up but the door locks didnt lock. I could hear what sounded like the module under the glove clicking but the locks remained unlocked. After some driving I tried it again and it worked like a charm. I then opened the drvers door and they all unlocked. Later that day I drove again and this time the locks locked but opening the drivers side or passenger side door did not unlock the locks as it normally does. Today was even worse, I pressed the key fob to unlock the car and the alarm chirped but the locks did not move. I had to manually open the drivers door with the key. I have the stick Jaguar alarm equipped with the original key fobs still in good working order.

After driving for some distance, I tried the locks and they didnt do anything. I then parked and had to lock my lock manually. Upon returning to the car, I hit the alarm button and the locks looked like they came up a millimeter but didnt move much after that. I got in the car and drove and when parking, I opened the drivers door and the locks started working again and have been until now.

Any ideas what this could be? I Have never seen this type of issue happen and I dont know if its the lock module under the glove or not. Dont want to buy another one without doing some checks first. Your help is much appreciated as always!

 

I have read repeatedly (and experienced) that a failing battery will cause "odd gremlins" in the electrics. Maybe run by a part store and have yours tested?

 

I thought that too but the battery is only 2 weeks old. I will take it by the local autozone to rule it out either way. Thanks for the tip!

 

Update=Battery checks out so it isnt the battery. Its also brand new.

 

Possibly check your ground straps/ cables? There are several, and a poor connection could make odd problems in a given area.

 

Any particular ones or place I should check?

 

There are 2(?) on top of the motor- front and rear intake side, there is one by each fuse box behind the kick panel, there is also one on the transmission tunnel left and forward a bit (as I recall) from the shift lever. I'm sure there are more but I'd think the ones by the fuse boxes would be more likely for your central lock issues. Also make sure your battery terminals and cable ends are clean...

 

Ok, so I checked the grounds, removed them, cleaned them, cleaned the contact points but the problem persists. Any other ideas?

 

Hi ETA,

Sorry to be late to respond to your thread, but one possibility that comes to mind is water ingress into the Central Microprocessor (CPU). The CPU notes when the front door locks or center console lock switch are activated and passes this status along to the Door Lock Control Unit. Water ingress into the CPU is fairly common with the XJ40 because the CPU is mounted on the firewall just to the right of the center console and just below the air conditioning evaporator drip tray. Its electrical connectors point upward. When the foam rubber insulation in the Climate Control Unit deteriorates over time, the foam crumbs clog up the drip tray drains, allowing condensation to pool in the tray and to slosh over the edge onto the CPU when cornering. Unfortunately, it takes a bit of disassembly to get to the CPU, but a starting point is to check for any moisture in your right footwell under the carpet. If you find any evidence of water there, your evaporator drip tray drains are probably clogged and it will be worth removing the CPU to inspect it for water.

Cheers,

Don

 

Hi Don and thank you for your response! I will be sure to check this and circle back. With the holidays upon us, I am surprised anyone has responded to this thread at all so much appreciated! I will report back with my findings.

 

Hi guys, so I havent had a chance to check the CPU as Don recommended given my torn ACL injury. But, I did notice something that may be the culprit of my problem. When the issue occurs where the locks all freeze and do not engage, the trunk lock does not work either. When the locks are working correctly and unlock when opening from the inside of the car, the trunk lock engages as it is supposed to when locking the car using the key fob, and it unlocks when using the key fob as well. I dont know if this is just a coincidence or if this is the cause of my issue. Any ideas?

 

Hi ETA,

I'm a little foggy-brained today and don't think I understand your question. You're reporting that when the locks are working, all the locks work including the trunk, but when the locks don't work, all the locks don't work including the trunk. What part of your report is the clue?

Cheers,

Don

 

Hey Don, sorry if my explanation wasnt clear enough, its Monday so I am a bit foggy myself lol.

When the locks are working as they should, that is when I hit the key fob button they all unlock or lock or when I am in the vehicle with the doors locked, they all unlock when I open the driver or passenger door, the trunk lock works in unison. So the button that you would normally push to open the trunk from the outside of the vehicle will lock or unlock when the system is working correctly.

But every time the system begins to malfunction with either frozen locks that dont lock or unlock, the trunk lock is the one lock that will not work even after I get the door locks in sync and working again. This leads me to believe that perhaps the trunk lock is to blame causing everything else to go out of sync? What do you think?

 

Hi ETA,

Now I understand. Yes, it does seem possible that the trunk latch is malfunctioning intermittently and when it malfunctions, it causes problems throughout the system. I can't remember whether you have cleaned and lubricated the accessible parts of the trunk latch, but it may be almost as easy to just replace the latch with a good used one from a salvage vehicle to see if the symptoms go away. Latches are often available at reasonable prices from salvage yards that sell on eBay.

Cheers,

Don

 

So a quick update. I moved the Jag to the garage next door which is temperature controlled. Now that it has been parked there, the door locks seem to work without issue. The trunk lock works as it should and all 4 door locks are fully functional. I took it out for a spin yesterday in 29 degree weather. I visited some friends and when I came out after a several hours of the car being parked in the cold, the door locks ceased to work. They were basically frozen in place which is so strange. Any ideas?

 

Battery in remote dying possibly?

 

I replaced the remote battery and it works even when the locks are frozen as I can hear the Jaguar alarm deactivating. Any other ideas?

 

Clean and lubricate the actuators and adjust the linkage if necessary. The tops of the door trim panels tend to deform from sunlight and the chrome ferrules around the door lock buttons tilt and pinch the lock button, creating resistance the actuators can't overcome.

 

Hi Don, I actually found your suggestion in a previous post you had replied to for another member. I took all the chrome ferrules when this first happened thinking it would help but nothing. I also lubricated the actuators and confirmed they are all functioning exceptionally well, except when the temperature drops below 40-50 degrees give or take.

 

So it looks like the problem persists even with the warmer temp in the garage, albeit only 10-20 degrees warmer than outside. I decided to buy a used central locking module for $40 to test it and see if that makes any improvement. It was cheap enough to try. I will report back once I change it with good news I hope!