Hi, first let me introduce myself, my name is Eugenio and I live in Chile, I have a Dakota 2002 3.9 4x4, a very good machine, but since I bought it it has had this problem, I changed the sensor that goes on the side of the automatic gearbox , but it stayed the same, I still can't figure out what it is, they told me it could be the gear lever cable.

 

Do you have the electronic display, or the regular, orange feller that moves behind some holes?

 

Check this video out.
If you already replaced the neutral/safety switch then your looking at pulling the valve body. Might be possible with the trans still in the truck.

 

What you are seeing on the digital display is the PCM not knowing what position the gear indicator is in. This is typically due to the plunger not moving smoothly or being stuck.

When the gear is indicated, does it always match the position of the shifter? What I see in your video is that it correctly indicated reverse, does not indicate neutral, then indicates drive. Is this always true?

If so, I would not anticipate this being a shift cable issue, though it could be. I would anticipate it being more related to the detent rod having some sludge stuck to it, or the sensor not landing in the exact right spot.

There is a "rooster comb" that rocks the shift detent arm into a position for each gear. This is to help remove the shifter and shift cable from any alignment error. That detent arm then pushes a detent rod into the position sensor.