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1972 Mark IV Power Door Lock Issues

Dear Bill,

I'm a proud recent owner of a Lincoln Mark IV from 6-1972.

I have a problem with the power lock system from the doors. The passenger door is stuck and will not be opened by key or by pulling from inside on the knob or door handle. They driver's side can be opened with key although keys are worn out little.

What could be the problem here? I would think that even if a relay or breaker is broken the door should be possible to open by key right?

With kind regards,



Greetings Alexander -

Some of these issues can be frustrating and because your car is a recent purchase the fact that you may not know the history of the door lock failure will make it harder to diagnose. This problem can be caused by any one of several faults within the door. The key that you are using could be incorrect for the passenger door because of a previous repair to the drivers or passenger door. There may even be some sort of hidden lock damage inside the door that cannot be seen from the outside if you purchased the car with that door not operating. The power door lock module could be seized inside the passenger door and subsequently causing the lock to become non operative. Does the drivers door power lock operate correctly? The lock mechanism or the remote rods inside the door could be seizing or are maladjusted. Sometimes removal of the lock mechanism and a complete cleaning and oiling of all moving parts can get the mechanism working as new. An experienced inspection of the inside of the door will probably be necessary to find the culprit.

Of course the door will need to be opened in order to remove the trim panel and gain access to the repair therefore you may need to seek the service of a locksmith who can trip the mechanism in order to open the door for you. If you are having a repair shop do the entire repair, that shop may have the proper "lock out" tools on hand. If we can help you further with any parts or advice when you have more information available, call our office and refer to your blog.