99 5.4

[2nd99Eddie]

I seem to be having transmission issues. While out driving a few weeks ago. The light on the shifter began to flash. No major symptoms.
Used my Bluetooth type scanner on it. It came back with P0781 and P0782. Checked the fluid. It was low from my interpretation. Added some. Cleared the codes. Some time later after driving a good distance. Loading a 6.5 ft X 14 ft open utility trailer the light flash again. This was after I had drove even further and had got emptied. I think the code was P0783. Added a little bit more fluid. Later on, I had stopped at the mailbox. Then proceeded to go on to the home. It was as if I bumped it into neutral. Bumped the pedal ever so slightly. It caught. Parked it. Fluid appeared to be right. The next morning it drove 7 miles. The slightest ever hesitation closer to the destination.

Tonight, started off with again that almost faint hesitation. I’m going to say I felt was more related to the air and fuel mixture being off. The more I drove it, it gradually got worse.

Fluid was ok. The codes changed up again to P0781 and P0782. For some strange reason the PCM wouldn’t register on the scanner. There was a malfunction with this “theft” system that prevented it from starting at first.

Which step should I take next? Is there a common problem (TSB) for this issue. I don’t want to go to a shop and be lied to.

Any information will be greatly appreciated

 

[TheWildMechanic]

I would check shift linkage under the dash. It gets loose and triggers the NSS, and it also causes the manual shift valve to only half open and only allow half pressure to your gears.

 

[AWAR]

I would also verify your shift linkage. The flashing light and those codes do not bring good news. The computer does not see the correct rpm change when it commands gear changes. It is always possible that the transmission needs the speed sensors replaced. I always look at data before going inside. I have a 4R100 in my 03 Navigator.