Still haven't solved erratic shift, inop and/or erratic speedo, flashing TCIL problem but I believe I'm getting closer.
In front of me is "1997 F-250 HD, F-350 & F- SUPER DUTY OWNER GUIDE". It came with this used truck 1 1/2 years ago. On page 23 the 2nd paragraph states,"Your vehicle contains a speedometer which receives its input from the Anti-Lock brake sensor [ABS mounted on differential housing]. The speedometer is also used to provide a speed signal for correct operation of the vehicle's Powertrain Control Module (PCM), electronic transmission, and speed control (if so equipped). Because of this it is very IMPORTANT to change the speedometer's internal conversion constant if the tire size on the vehicle is changed."
Mechanics at Ford dealerships use the "SERVICE MANUAL (POWERTRAIN, DRIVETRAIN" Only) for same vehicle. Page 07-01-27 says, "The programmable speedometer/odometer module (PSOM) receives input from the rear brake anti-lock sensor [ABS] which is mounted on the rear axle differential housing. The PSOM processes this input signal information and relays it to the Powertrain Control Module and the speed control module." This is what, ultimately, controls the shifting of the E4OD trans. If I can figure out how to get the speedometer (PSOM) out of the truck without entirely dismantling the cab I'll check it out and maybe replace it. I've already replaced the ABS with no change seen so ANY ideas will be greatly appreciated! I wonder how much the dealerships made by NOT issuing a recall on this commonly known problem?

 

Also...is the Vehicle Speed Sensor (VSS) often confused with the Anti-Lock Brake Sensor (ABS)? Especially on this truck?

 

Yes it is. One sensor for two jobs.

To change the PSOM just take the cluster out and then take the cluster apart.
This write-up is for changing to a tachometer but will work for changing the PSOM also:
Installing An OEM Tachometer In A 1992-1996 F-150 Or Bronco .: Articles

The PSOM:


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i have been told to check the wire from the vss in the rear. the wire gets rubbed through over the years of movement

 

If your speedometer works OK and your RABS lamp on the cluster is not on then the wire to the rear end is OK.