e40d speedometer & shifting probs

[90dodge]

I've got a friend with a 95 ps with an e40d. He has been having problems with a the speedometer jumping and sometimes the transmission erraticly switching from 2-3 and back while increasing speed until he is going fast enough to engage overdrive.

I have read that the speedometer jumping can be the vss, psom, or tone ring in rear diff. He replaced the vss a week or so ago. It is still doing it. Is there another problem that could cause both of these symptoms?

 

[12vf250]

Worn bearings in the rear end, the tone ring not running true or full of junk, missing teeth etc. I have also seen a lot of trucks with the harness from the frame to the diff broken, shorted, just generally f-ed up.

 

[90dodge]

From 94-97, do you use obd1 or obd2 to scan? His truck 95 is a 95 with 97 engine, also has the 97 pcm in it. He said it is obd2, but both scan tools he has tried (one being a ford tool) wouldn't communicate with the engine. Any ideas?

I don't really understand it, but maybe you guys know a secret that I don't.

 

[12vf250]

Sorry its taken me so long to reply. I forgot about this thread. All the OBS powerstrokes use obd2 . His truck thinks its a 97, so it may be as simple as using the VIN digits from the 97. I've never had any trouble scanning those trucks even with the wrong year put in the scan tool (snap-on). I would doubt it, but there may be a chance that the ECM and PSOM may need to be flashed together to get everyone to play along?