Door lock and interior lights

had 2 events happen at the same time
-central lock stopped working completely
-interior lights do not switch on when you open the front doors (they do switch on when you open the rear door)
I thought that was a faulty door lock control module, replaced it but still the same fault.
any hep out there?

What year and model???

Xj40 lefthand drive 1990

When you say that the central locking “stopped working completely”, do you mean that it doesn’t work either when you try to engage it using the driver or passenger door key locks or when you sit inside the car with the doors closed and operate the driver or passenger door lock buttons?

Using the key, only that door opens or closes

I thought the problem was locking, not whether the door opens or closes?
If only the driver’s door locks with the key and the other three doors and the trunk remain unlocked, what happens if you use the key to lock/unlock the front passenger side door?
If neither door works the central locking using the key, does the central locking work if operating the door lock button when inside the car with all doors closed?

Same behaviour as the drivers’ door
The lock button does not lock anything.
I do not hear the usual pneumatic sound when I lock/ unlock from any door… as if the car is not equipped with a center locking system.
Again this happened at the same tome when the interior lights stopped lighting when opening either of the front doors. They do switch on when you open either of the back doors.
It looks like an electric problem however I checked all the fuses and seems the fuses are ok.

Mmmm … The only thing I can see which controls all aspects of the central locking system is the CPU.

That CPU of course is also in circuit with the door opening / interior light function but I cannot see any obvious link between the two - so I’m snookered!.