What may be wrong with my central locking?

Question

My Skoda Felicia from 1998 has central locking (not remotely) which has problems. The doors can be unlocked through central locking from the front doors. However, the driver's side door only unlocks the rear right door and the passenger's side door unlocks all but the rear left door.

So, schematically:

                            Left Front   Right Front   Left rear   Right rear
Left front (un)locks  :         x                                      x
Right front (un)locks :         x             x                        x

What may be wrong with my central locking system?

Answer 1

Most likely a dodgy connection on one or more wires. The wires to and from each lock have to go through the 'snake' connecting the door to the bodyshell, and this typically is the most likely place for failures to occur, particularly on the driver's door (the one opened and shut most frequently, twisting the wires more and thus fatigueing them more).

Depending on the design, you will probably have a multi-plug at one or both ends of the snake - you should be able to use a multimeter here to figure out if any of the wires have broken. Hopefully you'll then be able to replace the offending wire, or repair it.