4200 driver's side door lock that doesn't

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342
I reckon you've got one or two failed lock modules


C

Sounds quite feasible, with the drivers door being the more likely culprit if it’s only a single fault. Odd coincidence to have two fail at once.

A possible second problem could be that the door lock mechanisms are not attached properly to the operating rods causing inconsistent amounts of travel. Given the other mechanism I found disconnected, it’s entirely possible. Looks like time to pull the door card again and take a second look.


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342
What about wiring? Could a frayed wire in the door jam cause your problems?

Also feasible. From the drawings it appears there are only two cables: one from the inside door handle to the front end of the door, and one from the external handle to the lock itself.

Going to have a hard time sleeping tonight knowing there are solid troubleshooting leads to follow.


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Oneball

Member
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11,075
Also feasible. From the drawings it appears there are only two cables: one from the inside door handle to the front end of the door, and one from the external handle to the lock itself.

Going to have a hard time sleeping tonight knowing there are solid troubleshooting leads to follow.


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I hate that I woke up in the middle of the night yesterday thinking “I should have put Loctite on the crank pulley bolt” even worse is I’m not at home to do it for a week.
 
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I hate that I woke up in the middle of the night yesterday thinking “I should have put Loctite on the crank pulley bolt” even worse is I’m not at home to do it for a week.

And they say Anxiety is a bad thing. Without a proper measure of it, nothing would get done right!


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342
One. Step. Closer.

Pulled the left (drivers) door card and checked all connections. All is well, since the reconnection of the lock bar as discussed above. But still, the doors won’t electrically lock except... when they do.

I turned off battery power for some stereo work, and on restoration, the remote lock worked exactly once. Repeated this again and again to be sure. After one successful cycling, no more. Cycled locks using the inside controls and notes a solenoid noise in the driver door that does not ever occur in the passenger door. It may be the passenger door after all!

On a positive note: replaced the four main cabin speakers (not the rear deck) and the stereo sounds... more than sufficient. Not for me, of course, I prefer engine noise, but we have a road trip to the Hoh Rain Forest coming up and Mrs submariner prefers tunes to V8 drone. So shall it be written...


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342
The holidays behind us, and a few days off, decided to wade back in to the fight. Reread all of the previous forum posts here about door locking and remote lock/unlock issues, and did some more troubleshooting.
  • disconnected each door completely (large connector at the hinge). Neither door would lock/unlock remotely with the opposite door disconnected
  • lubricated and cycled both door locks multiple times. Operation is smooth, with only an initial reluctance to move if turned rapidly, faster than the electrical system can keep up
  • Cycled locks multiple times from the interior and exterior to look for patterns.
Complete symptoms (documenting as much for myself as I am for anyone else) - verified with two different 184391 door lock/unlock ECU modules with identical results:
  • Remote unlock never works.
  • Remote lock can be made to work once, but the driver's lock switch at the door handle indicates that the locking event on the driver's door is only halfway executed. This could be a mechanical adjustment issues, as the solenoid is clearly firing.
  • Passenger door unlock event has no effect on driver door, returns passenger door to locked position.
  • Passenger door lock event halfway locks driver door.
  • Driver door unlock event fails to open passenger door, returns driver door to partially locked position.
  • Driver door lock event locks passenger door successfully.
Based on this, decided that disassembling the driver's door made the most sense. Pulled the two electrical connectors for the door lock in the driver's door. Attempted remote operation - no response by the passenger side door lock or the door lock/unlock ECU. (Recall that earlier it had made a click with a 1 sec period when passenger and driver door locks were misaligned). No problem with manual lock/unlock of either door in this configuration.

Conclusions:
  • There's still more than one fault. One clear fault lies in the driver's side door locking event, as it is only partially locked when activated by remote means (use of the remote, or by locking the passenger door). Suspect this is a mechanical problem of adjustment between the solenoid locking device, and the lock itself. Will investigate if this makes sense - not sure how the solenoid and lock are connected yet
  • No electrical unlock signal is heard when the remote is used. Not sure where this problem lies, but first guess is within the alarm controller.
  • Door lock/unlock ECU is not the problem, since symptoms didn't change on changing out this part.
First step - learn about the door locking solenoid and how it does its job.
That was quick. Checked out the drawings on Eurospares, and it appears the solenoid actuator is embedded in the lock mechanism itself.
 
Last edited:

CatmanV2

Member
Messages
48,549
Driver's lock unit is failing / failed. Never ever heard of an adjustment problem. They just get weak, and the actual lock has the solenoid built into a single unit.

There may be another issue, but fix this first. In suspect the ECU is getting confused about what's locked where. The status is communicated by microswitches so it's pretty simple

C
 
Messages
342
Driver's lock unit is failing / failed. Never ever heard of an adjustment problem. They just get weak, and the actual lock has the solenoid built into a single unit.

There may be another issue, but fix this first. In suspect the ECU is getting confused about what's locked where. The status is communicated by microswitches so it's pretty simple

C
Concur - after noting there isn't anything between the solenoid and the lock itself. Ordering that up presently, and once that's in... will continue to pursue the unlocking issues.
My engineer brain wants to put a tech on this to write a flowchart!
 

Twinspark

Member
Messages
460
Anyone know if a failing door lock affects the wjndow dip mechanism? I’ve got a failed drivers door that shows the exact symptoms, have not gone around to fitting the new lock yet.
 

CatmanV2

Member
Messages
48,549
Anyone know if a failing door lock affects the wjndow dip mechanism? I’ve got a failed drivers door that shows the exact symptoms, have not gone around to fitting the new lock yet.

Don't think so. I think it's the switch in the handle.

Could well be wrong, though

C
 
Messages
342
Anyone know if a failing door lock affects the wjndow dip mechanism? I’ve got a failed drivers door that shows the exact symptoms, have not gone around to fitting the new lock yet.

There are position monitoring microswitches in the door that detect the exterior and interior handle positions, as well as the key lock position. Try all three methods to see if any of them initiate a window dip. That will rule out the microswitches, or figure out which one has failed. But this is a second problem, in addition to your door lock/unlock problem.

If you're having symptoms similar to mine, with regard to lock/unlock and partial movement of one of the locks, then looks like you've got a failed electrical portion of your door lock mechanism. Eurospares has them in stock, Scuderia had a 12 day wait. I intend to replace my lock, but then rebuild the electrical portion of the removed lock, for future use if needed. Should just need a disassembly of the small drive motor, cleaning the rotor, and new lubrication. If you've got the time and temperament, you could attempt to repair the small electrical motor as your repair, I'm just doing it to see if I can. Locks are inexpensive enough that it's not much of a sacrifice.

Happy to exchange DMs on methods to troubleshoot the locking issue.

Good luck!
 
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342
Update: fixed.... partially.

On the positive side, I’m an absolute expert at door card removal and reinstall action, though one of my tweeter speaker clips is now sheared off due to overuse.

Changed out LH door lock with new unit from Eurospares. Door locking with remote is now successful! Unlocking, however, is not. LH door unlocks, the locks again as the RH door failed to unlock.

Sounds like the RH door lock’s unlock solenoid has failed completely as it doesn’t even attempt to unlock. Just to be sure, swapped out the lock/unlock ECU with no change in symptoms. RH lock is now on order.

This makes three total faults since beginning this troubleshooting: one disconnected linkage in the LH door thanks to the dealer replacing door locks improperly, the LH door unlock solenoid too weak to fully unlock the door, and now the RH door solenoid for unlock completely failed.

As I was just explaining to my better half, I thought I was purchasing an exciting and beautiful car, little did I know I was purchasing years of weekend projects!


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342
The level of satisfaction gained from remotely locking and unlocking the Coupe may be irrational, but that doesn't make it any less enjoyable.
RH door lock changed out over the weekend, and now, all faults removed, the doors lock/unlock by all means, flawlessly. Though now I have a tweeter that needs a replacement housing, at the very least, due to breaking off one of the two clip protrusions. Never a completed "to do" list - the joys of Maserati ownership.

If anyone ever needs assistance in troubleshooting door lock issues, I'm happy to help.
 

Soenvious

Member
Messages
128
Resurrecting this thread as I've just completed this job on my 4200 CC.
Problem showed as not being able to lock the car with the fob but it would lock with the key in the drivers door. If I tried to lock the car with the key in the passenger side it would lock and unlock immediately. Decided it was the driver lock that would not drive fully home with the solenoid, so that's the one I changed. Result.
As a side note the lock mechanism was a reasonable price, considering some of the 'silly' prices charged for other bits on these cars, Thank you Maserati.:p