From browsing your blog, it seems like you are as close to an expert on Lincoln’s as can be. recently I bought a 1979 Mark V. The driver’s door lock is frozen and the key will not turn it. The knob inside will lock the door however. My thinking is it’s the cylinder. The question I have is with that light thing on the outside of the door that’s supposed to light the keyhole at night. I have the interior panel off but am reluctant to try to take the lock cylinder out as i cannot see how its connected or works with that light. Is the cylinder attached to the light or is this a special cylinder that has the light built into it? The previous owner left the shop manual and it tells how to take out a conventional lock cylinder, but it makes no mention of the light.
Also, another problem you might be able to point me in the right direction on is when either car door is opened, I hear a soft clicking every few seconds, I noticed the knob on the seat back jiggles with each click. Do you have any idea what this is all about? Seems like a lot of people on your blog have electrical problems with their Lincolns. Hopefully you will have come across these couple I have here. Well, I would appreciate you emailing me any info you may have on the above things.
I have consulted with our technicians regarding your problems and have found out the following. The lighted door lock cylinder assembly is removed in the same manner as a conventional non lighted one (as your manual describes) but with the addition that you must disconnect the electrical connector at the unit. Therefore, if you have determined that the cylinder has become seized and that the key that you have used is correct for the ignition cylinder and the other door cylinder then you should remove it and have a locksmith repair it for that key.
The cycling action of your seat back release solenoids has historically proven to us to be caused possibly by faulty solenoids. However if both sides are cycling when their door is opened I would test for a voltage drop in the system at the battery or any relay or switch involved. Our technician also has advised me that the Shop Manual describes the test procedure for these Automatic Seat Back release systems. Your manual if it is the correct FoMoCo shop manual should also show this for you. If you need any further info. etc. please do not hesitate to contact us.