I'd recommend you roll the windows all the way up and remove the inner panel or compartment depending on what you have with the 8 screws that hold it in place and look up inside the door while someone pushes the button on the outside of the door. It's all physical mechanisms that you can observe and see what is/isn't working.


When you push on the outside door release button it presses against the top of the arm that is the door latch. Here's a picture on DC website of what it looks like. Pushes against the very top of the lever.


Door Lock Assembly-L Hand | Dennis Carpenter Ford Restoration Parts


Any wear in the parts over the years can cause the mechanism to not move far enough to release. See if you can operate it by reaching up inside the door and push on the same lever. If it opens like that but the outer button doesn't operate it far enough then the button shaft might be worn short or rusted off. The outer custom cab door handle escutheons can be added to any of these trucks but requires a longer rod inside to actuate the lever enough. They come with the required buttons as you can see.


Door Handle Name Plate | Dennis Carpenter Ford Restoration Parts


My outside handles were not working very well so I took them completely off and removed the buttons and found a bunch of very fine dust built up around the button rod where it passes through the door handle. By cleaning the dust out and lubricating it there hasn't been a problem since. The original owner lived at the end of a long dirt road in a very dry, dusty area.


Hope that helps.


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red66rider, now others will probably know better than me as I'm new to these trucks.

But the way the latch/lock works is that part 21812 is the latch and actual lock.
If you put the lock in you will need the linkage rod that connects to the 21812 latch/lock, it moves a lever up and down, the same lever is moved by pushing the inside handle forward (or is back can't remember).
On your passenger door, its the same latch it sounds like the button part is not pushing the top lever that releases the door.

Here is a link to the latch/lock, if you see the lever on top is the one the outside door button pushes.
Door Lock Assembly-L Hand | Dennis Carpenter Ford Restoration Parts

 

Thanks for the help... seems like a straight foward fix; just have to find the problem.