440T - Doors lock doesn't wowrk

My dear firends.
I have a 1991 440 Turbo with 250.000 km. It's starting to bring me new problems everyday. The latest one is the central doors lock wich only works once in 100 times I open/close the doors with the key. I really don't want to spend much money to solve this problem. Any ideas?
Thanks a lot.
Henrique

[mollusk]

Hi there Henrique,

I'm not too sure if you had remote central locking in 1991 on Portugese models but I will assume you have the standard central locking where all doors lock or unlock with the key in the drivers door.

Very basically each of the passenger doors (and hatch door) has an electric motor that can activate the lock. The drivers door has a 'master' switch (it looks the same as a motor) connected to the lock linkage.

Operating the key not only operates the lock but the switch as well - which in turn operates the other lock motors/locks.

If the other doors all lock/unlock ok (when the system works) we can assume the lock motors are working. Suspicion must fall on the drivers door switch or the central locking relay (or the wiring between).
The door switch is accessed by removing the door panel. The relay for the system should be located behand the drivers footwell panel by the A pillar. Check the relay first for loose connections and for water corrosion - It's not unknown for water leaks in this area. Check the switch for loosness and test it. (it's a simple switch and you can test continuity with a multimeter). I could simply be that the door switch has become loose so the key is failing to operate it each time.

Hope this helps a little, Mac.