We have a 1992 500 SEL and a niggling problem started the other day. On pressing the remote central locking button control the red indicator light on the drivers door (also same problem on passenger door and boot) repeatedly flashes and the central locking does not function. The same is true from the interior locking button. The car operates from a hydraulic system and given the fact that there is no operation (or sign of movement) from the door locks, I assume the issue to be electrical. Any help / guidance would be truly appreciated - i.e. is there a relay? Which fuses function from the system? etc