Bongo Fury

I have a 96 2.5Td 4 wheel drive.

Central locking from drivers side. Doesn't look standard as the wire that runs from the door to the body sits outside the main loom.

Has been working fine, but now dropped.

The locks all lock as the car drives, so it's not power and the actuator is working. So the actuator can receive a signal and operate, but can send one when the drivers door lock is locked or unlocked.

It was intermittent but now failed. Any ideas?

I don't think it's broken wiring as they lock when you drive away.

It’s not unusual for the wire to break inside the insulation, caused by 'work hardening' as the door opens and closes over years.

Possibly someone has already done a repair, hence the extra wire outside the loom, and that has now failed.

Sounds like you have an alarm/remote fob system fitted as well ? It will be the this system triggering the central locking unit to close all the doors. The key lock/unlock sends a signal to the central locking unit when the key is turned on the drivers door, this signal triggers the central locking to close all the other doors. If you have an alarm or remote fob fitted then this also taps into the signals and will have its own wires to a solenoid mounted in the drivers door, this operates the lock instead of the key, which in turn unlocks/locks all the other doors.