Good evening All,

I'm having some issues with my XK8 coupe that have been ongoing for quite some time now and I cannot diagnose. I have done a lot of searching for answers, most of which point to the door microswitch or the Security Locking Module but none answer my questions - apologies if there are threads covering this but they don't come up. I have ruled out the microswitch and I don't think it is the SLM.

Symptoms are as follows:

• Central locking no longer works on the key. The indicators will flash, the passenger door will lock but then immediately unlock and lock again, cycling like this for about 5 times.
• The alarm will sound after the 5th lock/unlock, and will disarm on pressing the unlock button.
• The drivers door makes no attempts to lock/unlock when using the fob
• Initially when these problems surfaced the windows were also behaving strangely, such as going all the way to the bottom of their travel when using door handles and then not responding to the window switch, this was all after a period of non-use so the battery was low. The battery is now fully charged and all testing has been conducted in that state.
• The driver's door will lock/unlock using the key - but there will be the 20 warning chimes inside before the alarm then sounds (again, button will disarm either before or after alarm sounds)
• The driver's door handle can be pushed to lock and I can hear relays clicking
• If the driver's door is locked on the key, the passenger side will lock too (currently my only way to lock the car)
• The boot can only be opened once the driver's door is unlocked - it will not operate on the fob button (as the driver's door doesn't respond to this

I have tried a good known microswitch, it's creating a circuit and operating as it should.
I have had the SLM out of the car and there is no visual problem with it. The keys are both recognised by the car, it is not an issue with the keys themselves as both work.
The car runs, drives, etc otherwise fine, it is purely the locking issue.

I have bought a replacement door latch mechanism just for the microswitch (unfortunately the only one available was a passenger side, so I just swapped the switch) so already a few ££ into this, really need to get to the bottom of it as I am running out of options/patience. Any help would be appreciated.

 

If you are inside with the car running, do the locks behave normally? By that I mean they both lock when putting the car into gear. You can push the handle in and both doors lock / pull the handle out and both unlock with no strange behavior?

If it all works like it is supposed to when the car is running, I would say check / change the battery. All manner of strange stuff happens with a questionable battery in these cars.

 

My SLM got ruined by hydraulic fluid that dripped down from the pump, key fob stopped working and alarm went off randomly as well.

 

Unfortunately the symptoms are the same with engine running or not. I know the battery plays havoc with systems but in this case, it's been ruled out.

 

Have you performed a hard reset on the car?

Guys
JagRepair.com - Jaguar Repair Information Resource

 

Hi Gus - I hadn't, but just have. No joy.

Could this be caused by a faulty actuator on the driver's latch? If the driver's door is unable to lock (and clearly there are signals being sent to tell the car to lock as proven by the passenger side and the clicking of relays on the driver's side) would the car attempt to lock several times then sound the alarm?

 

The drivers side latch has several switches and one motor that locks and unlocks the door latch. You need to check all of them for open/close operation and also check that the latch movement is clean and lubricated. I have additional information but it is not with me at the moment.

 

The SCLM seems to be working in that it locks the Pass door.
Can you hear the driver's door lock actuator moving when you press the fob? If it doesn't move, either the actuator is faulty or the signal from the SCLM is not getting to the actuator.
Easiest to see with the door panel off.

 

No, there's no noise from the lock/latch area, just the relays in the door.

 

There is only one Door lock relay, so use a DVOM and see if you get a signal on the SG wire at the actuator when pressing the key fob, door must be latched.
Could also be a problem with Drivers door control module not supplying ground to actuator.