I've had a ford cougar but the central locking isn't working. My key has 3 buttons on It.

When I press the lock button on the key, nothing happens, if I lock the door with the key only that door locks still no central locking, if I press the boot open button on the dash, nothing, but I can open the boot with the key ok.

As nothing works I'm assuming it may be a fuse, but in my manual it doesn't say which fuse is for the central locking. Also, at a glance, my fuses look ok.

Is this a common problem with a nice quick fix or a bigger problem?

Any help would be fantastic,

Thanks in advance.