Gremlins in my doorlocks...help please !

I had a not entirely dissimilar issue with the doors on my 550. When I locked them, using remote or key, they would unlock about a second later. Sometimes! Intermittent faults are the worst.

Investigation revealed corroded connector plugs and brittle wiring inside both doors, necessitating a fair amount of replacement.

 

Strange. From your description, I'm not sure what is happening. In some cases, can you get one of your doors to actually remain locked, but the other not locked? Do the door locks work using the lock switches on door arm rests every time?

There are a number of things which might stop your door locking:
Sometimes doorlocks will attempt to lock, but will unlock immediately if one door isn't properly closed and "latched". There is a sensor inside the doorlock (which sometimes fails).
Sometimes a doorlock actuator is weak and won't move the actuator plunger far enough. In this case, the plunger will usually go back to it's original position (there is a spring in the actuator).

These lock systems are quite complex and difficult to diagnose. You may have to keep replacing parts until one fixes it. e.g. a doorlock actuator or a door latch ... or take the car to a dealer who has the appropriate diagnostic tools. According to the wiring diagrams, the Window/Door controller has a diagnostic port.

I haven't been able to figure out which microswitches/sensors correspond to those in the wiring diagrams yet... As you can see from the parts manual, there are quite a few

https://www.ricambiamerica.com/car-diagrams/ferrari/v12/gt-group-2-seat/550-maranello/doors-opening-control-and-hinges.html

 

My 550 had the same issue, no parts were needed, just cleaning and re-lubricating(not by me.....i'm useless)

 

My technician regularly lubricates and Checks everything .... Never had a problem

 

I have had exactly the same problem. It turned out to be the mechanism as seen in the diagram 118, items 27-30. This should move easily, but the grease that was in there was hardened so much that it barely moved. So took it apart (not difficult, but quite a bit of work, it requires removal of the door inside cover) cleaned the whole thing, new grease and it works likes a charm again.
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When the door is locked with the remote on a 550, does the locking mechanism backdrive those linkages to the lock lever on the armrest, moving the lever? Is the lever a visual indication of a locked door like the buttons on the windowsills of other, "less exotic" cars"?

If so, it makes sense that those sticky linkages in Bert's image would interfere with the remote locking system. The electric actuator would have to fight the dried grease. I suppose in some cases, you could exercise the locking lever to loosen up the dried grease as a temporary measure. However, I believe there is a limit on the number of times you can do this, otherwise the electrical doorlocking system will be inhibited.

Anders, do you get the same intermittent behaviour if you use the electric doorlock switches?

When the door is manually locked using the armrest levers on the 550, does the electrical system assist the manual locking? I'm just wondering if it's the function of sensor in the armrest (part 22 in the diagram) to sense your intention to lock/unlock the door. On my 355, when you lock the door with the key, the electrical system assists the manual locking. Because there are so many components to move, it makes the locking process easier.