Other than getting the door panel off I would get a can of WD40 with the nozzle and spray the dickens out of it up through any opening that you can get to. The try to work the lock up and down, then spray some more.

Before anyone says it I know that WD40 isn't a lubricant but it also doesn't make a huge mess when doing a shotgun spray.

 

Doesn't opening the door using the inside handle open the door and unlock the lock?

 

Thanks for the thoughts. I drowned the door internals with WD40 through the lock riser hole and the interior handle will not open the locked door; it's disengaged when locked. I removed the other door panel to see how the latch works. My next step is to see if a locksmith might be able to open the door. If not I will have to make a tool to reach down through the window slit and open the door at the latch.
Happy Trails

 

I know for fact you can remove the inside door panel with the door closed. Not the funnest job in the world, but it can be done. That'd give you much better access to check out the lock and maybe get a better grip on it.
AaronSEIA

 

Did the other latch have a rubber boot over it? They both should, which would make spraying from the top ineffective. Front latches got the boot in '93:



The best place to spray is through the outside gap, and around the strike bolt into the latch jaws.

Are the rear lock motors the old steel style, or the new plastic ones?



You said you had that door panel off before - why? Did you ever R&R the lock motor from its spring bracket riveted to the door skin? They're very difficult to reinstall correctly.

 

Thanks for the reply Steve.
I have been inside these doors many times over my 20 years with the truck. Typically to clean and lube the window. I lived out on a remote desert and had severe dust and sand problems. The lock motors are original. One new bit is I made a hook tool from the small stainless bar found inside of wipers and reached down at the rear of the door from the window opening to where the lever that unlocks the door is located. I hooked the metal part of the lock connecting rod bent through the lever (held with the plastic clip). It is frozen solid. I had at least 30lbs on it and the stainless bent open. I see a lot of rust. I sprayed the WD40 rust product all over and after 3 days and several repeats that door is stuck shut.

At this point I will have to pull the seat and panel to get the door open. But that will have to wait a week or two. I'll repost after I get it open.

Happy trails.

 

I lived out on a remote desert...

Why not put it in your profile?

The lock motors are original.

That doesn't answer my question.

I see a lot of rust.

What desert causes lots of rust?

...that door is stuck shut.

Are you sure it's not just locked?

 

You don't need to pull the seat to get the panel off, been there, done that.
AaronSEIA

 

For what its worth.

I have a 4 door dually (97 powerstroke diesel).
Rear doors would sometimes unlock, othertimes never. Very frustrating cause you never knew when it was going to happen.

What worked for me.
I purchased new and replaced the 4 plastic lock covers that stick up above the door. I'm sorry, I don't know the technical jargon.

I have had no problems since then.

Why did it work? The vertical rod that goes up and down has a short 2 inch plastic cover that screws on the top of it. The top is what you see go up and down when you lock and unlock the door.
Apparently, the rear door vertical rod was out of alignment just a bit. It was causing the plastic cover to hit the underside of the door and push its way over a little and up as it found the hole. Eventually, the plastic was chewed off the plastic cover on that one side. So instead of going up into the hole (unlocking), it was hanging on the inside of the door panel (not unlocking).

When I put the new covers on, it caused the vertical bar to move over enough for the plastic cover to clear the hole.

Just compare your black cover on the top of each lock and see if any are chewed, broken, or chipped.

 

...plastic lock covers that stick up above the door. I'm sorry, I don't know the technical jargon.

"Sill button"

...the plastic cover to hit the underside of the door...

That means either it was screwed down too far onto the rod; or the Z-bend in the rod was bent too much, causing the rod's effective length to be too short. The sill button should never go UNDER the door panel - it should stop just ABOVE flush with its bezel on the panel.

 

I think in my case, the original owner must have been backing off (unscrewing) the sill button each time it chipped until eventually it chipped too far.

Since I usually drive alone, I never noticed I was adding to the problem.

Once the one door couldn't unlock anymore, the problem became a feedback loop issue through the electronics (I'm guessing). Then even if I unlocked the driver door, the rear doors (both) would fail to unlock). Sometimes it would only be the one with the chewed up sill button.

Whatever the case, it is certainly something to consider. I used a small flat blade screwdriver to encourage the vertical rod to reposition so it would come up through the door like it was supposed to. Purchased new sill buttons all the way around, and replaced them. I did have to use a pair of pliers to unscrew the busted sill button. But it all worked out.

Good luck with unlocking the door.

 

No, there's no feedback, and no loop. All the lock motors are in parallel. That means each one tries to work, regardless of what the others are doing. But there are many common failure points in that circuit; the front PASSENGER lock switch being the most-common (because it doesn't get used enough).

 

Hello and thank you all for the help and advice.
I wanted to finish the story. In the end I was able to remove the rear door panel without removing the seat. It took some time and patients but I don't have a place to work on a truck now and had no place to put the seat if I removed it. I jockeyed the seat back and seat to the max forward and max aft positions to access the panel. The door panel will have to have 3 of the plastic gizmos for holding the plastic push things repaired but I am good at that now with JB Weld. I've rebuilt these all at least once in the last 20 years. The window actuator was frozen to the extreme. Once I drilled out the rivet and put it in a vice it took a maximum pull with vise grips to get the jack screw to turn. But the electrics are tango uniform so I'll be replacing both rear doors actuators. But for me the good news is my door works and I can lock/unlock it.
Happy Trails

 

...how you were able to open the door to remove the door mechanism? Your reply bounced from the door mechanism to the window actuator and back to the door working. So I missed how you got the door open.

I think it's there in his last reply:

...remove the rear door panel without removing the seat. ... I jockeyed the seat back and seat to the max forward and max aft positions to access the panel. The door panel will have to have 3 of the plastic gizmos for holding the plastic push things repaired... ...I'll be replacing both rear doors actuators.

 

Hey Steve are you still on this string? I realize it has been 4 years.... I have a 1996 F350 with the same problem but a front door and I have a question as to how you were able to open the door to remove the door mechanism? Your reply bounced from the door mechanism to the window actuator and back to the door working. So I missed how you got the door open. Thanks