Thank you Meirion1. I have put it all back together and I am going to wait until I am back in the UK for a few weeks end of June and pick up a second-hand one there. I don't mind paying for a replacement but the price doubles if I have to have it shipped here!
At least (thanks to the help I have received) I now know exactly how to remove and refit!!

EsRay, before replacing your door actuator, test it again by applying 12v to pins 5 & 6 using an independent 12v power source, NOT the cars actuator power supply plug.
An independent power test is necessary because the cars locking control module may currently be supplying no power or incorrect polarity because it is not synchronised with this actuator.

If your actuator still does not operate with an independent power supply, then you can assume its has a faulty motor or micro switch.

However, if the actuator now operates with an independent power supply, you will need to synchronise it, by opening the other 3 doors & then setting your removed actuator into its 'open' position, using your independent power supply. (The open position can be determined from the position of the actuators locking' teeth)'.

Replace the actuator back into the car door in its open position before connecting the power supply plug & all doors should then be synchronised with the control module.

[QUOTE=henry crun;2055837]EsRay, before replacing your door actuator, test it again by applying 12v to pins 5 & 6 using an independent 12v power source, NOT the cars actuator power supply plug.

Thank you Henry. Please forgive my ineptness, but I have studied the wiring diagram and I appear unable to decipher which pins are 5 & 6?

Am I being really stupid here? There are two connectors on the Actuator and is it obvious which pin is pin 5 and which is pin 6 on which of the two?

Pins 5 & 6 are located inside the large female connector and are labelled with small adjacent numbers (as I recall). (You can also identify these pins from the end of the car cable plug connector.

Henry, thank you for all of your help.
I have already put the door back together because I need to use my car, but I plan to take your advice and undo the damned thing again just before I go to the UK for a 3 week break; that way, I can check whether it is really dead and then leave the door card etc off until I return with a replacement (should this prove necessary). Our apartment building has excellent security staff, cameras everywhere etc, so I am not worried about leaving the door unlocked.
Again, thanks.

I just fitted a used lock from Autoreserve, ~£25. Works perfectly. Came undressed, ie. missing some plastic mouldings that I had to transfer over. But whereas the original is powdercoated black (and externally looks as new), the replacement was unpainted, and looked a bit scruffy. Both are stamped "Ford". So I'm wondering if the used lock might not have come off a X350, hence the missing plastic part (I can't understand why a breakers would take that off a car).

I just fitted the lock, none of this synchronisation.. Very easy job it proved.

The process was educational. Unbelievable number of completely different block connectors in one door. The locks I replaced and fitted had two block connectors, with a smaller one for maybe the deadlock? Lack of standardisation in connector blocks probably doesn't help electrical system reliability.

Ispab, thanks. Is this what you bought:

eBay

Thanks for the nice info on actually how to remove the cover and get to the actuator...

My door problem is that suddenly one day, the front passenger door inside handle does not work. The handle feels disengaged from the lock. I can push/pull the levers, but the door will not open/lock/unlock. After removing the screws holding the door panel, I proceed to disconnect the connectors in the attempt to remove the panel to get to the inside cover. However, I found the door cable between the door lever on the door panel and the lock actuator actually has broken. I was able to pull the panel away with the broken steel wire just came out within the door cable... Looks like when the car came out of the factory, the cable assembly was off from the correct opening designed to allow the cable to come out between the metal and the inside cover. After years of rubbing, the wire finally broke at that spot. I was unable to find the part number for the door cable, only the actuator. I don't know if the cable even comes with the actuator as the description of the actuator says "no cable"??? Without the part number of the door cable, I was unable to get new part. I found a used one on ebay and got mine fixed. Anyone who knows the door cable part number may want to post it for others....

Note: I only need to remove the 3 screws hold the door actuator to remove the cable connection on it. There is enough play with the exterior door handle connection that you can still get the actuator to a position to remove the door cable without disconnecting anything else.

Reinstall..
 

As an addendum to this fantastically helpful thread, on some models you may find a 'security shield' made of aluminium which gets in the way of the latch. The lower part of this slots inside the upper and is held in by 2 torx bolts, one to the upper shield and one to the door latch. To remove the latch you will have to first remove the lower part of the shield, and rotate the latch mechanism clockwise to bring it out from the upper part of the shield.
Replacing the latch involves placing the latch inwards to the car and rotating it so it slips in front of the security shield.. Don't fight the shield as I did for an hour, just slip it behind from the side by rotating it anticlockwise!!! There is no need to take the upper shield out or undo the upper shield top bolt (accessed through a hole on the inner door panel)

Hi all,
On my x350 2004, the passenger door (LHD) is locked. No matter how I try there is no sound of the lock when pressing on key buttons or inside the car.
I also reprogrammed different modules by using SDD, nothing helps.
How do I open this ,,,,,, door?

Does the key work to unlock and then the external handle work? If yes, have an actuator failure. If not, then that sounds like a complete mechanism fail.

You should always be able to use the key and external handle

When I turn the key in the driver's door (only door with a keyhole) everything locks or unlocks except for the front passenger door.
I had another person trying on the outside while I tried on the inside and simultaneously pressed the key buttons.
It's probably a complete mechanism failure.

What to do?

Ah okay, no passenger keyhole. Then I think you have a difficult job of removing the door card from inside the car. It's doable but tricky. Then you should be able to opetate the mechanism from inside

Svannie do you use double locking? ie when you can't open the door from inside or outside

also when you use it it closes the door mirrors at the same time.

I never use double locking.
However, I think it is probably double-locked now, must have happened by mistake during my attempt to unlock the door.
I will take the driver's door apart and try to see how everything is attached.

The fault is probably a failed microswitch.

Sometimes when they fail they fail intermittently before complete failure.

Walk away from the problem for a while then try again to see if it opens

You may be lucky like I was!

I just looked at the circuit diagram and it looks like only one fuse for all door locks F13

so it can't be a fuse.

I suggest that you double check that -I can't find a separate fuse for front locks in the list in driver's hand book.

I suggest that you don't dive into the door before you know what's involved in a repair.

Hi svannie,

At the link below, you can download the wiring schematics for your car:

Jaguar X350 Electrical Guide 2004

Cheers,

Don

Have walked away for a while, but it's on my mind all the time.
I came back and pressed, pulled and pushed but, it won't unlock.
I removed the rear upper part of the passenger door panel/card and stuck a hose through the upper hole and aimed at the door latch, flushing it with hot water. Thought the heat could help, but no.
The Electrical guide will be useful to have (thanks Don).
It looks like there are no other fuses, only F13 power for the REM.
Now I will take a break, relax and study the Electrical guide.:)

"flushing it with hot water".
Gulp!

A hot air gun would have been better.