I have a 95 F250 7.5L/460 4x4 I just bought with only 85k miles. It drove fine until the other day when I noticed the speedometer & odometer where not working, the o/d light was blinking and it was shifting really hard.

Per other threads I checked the fuses which were all fine. I then replaced the vss. I fired it up and everything worked, drove it 2 miles to town and it shifted better then before!! On the way home however the same problems came back! I checked the vss connection and it looks fine.

I then took out the PSOM hoping to find some bad soldering but it looked fine.

I put it back in and started up the truck and the odometer worked again and I could tell the speedometer was working to because it came off the post. I put in gear and boom...no odometer/speedo again. Oh and the temp gauge was all the way to the left( out of normal position and not working); i'm guessing i didn't get it back in correctly.

I can't figure out why it works 1 minute then quits again. Any ideas??

 

You should probably check for codes first off.

 

check the plug on the mlps(neutral safety switch) on driver side of trans where the shift linkage goes to.had the same problem mine was slipping from time to time.

 

https://www.ford-trucks.com/forums/1...s-but-why.html

 

Vss sensor on rear differential

 

Ok..so i checked the plug on the mlps and it looks and feels fine...not sure how else to check it.

I pulled the codes and I have code 452 - vss signal to small. So it appears to be vss, but I replaced it so did I get a bad one or do I have a short in the wires?

Anyone know how to test vss or electrical short? All I have at my disposal is a digital mutimeter.

 

It should produce a small amount of ac voltage when the driveshaft turns, I think about 1/4 -1/2 volt. There is also a resistance spec, google should find that for you. Could be a broken wire between the comp and sensor. Check the wires where the move as the rear suspension moves.

 

Ok..sorry it has taken me awhile but I live in the midwest in the cold and working on this outside isn't very fun..anyway I took the vss back to the store and exchanged it hoping I had gotten a bad one.
No luck so I inspected the wiring and again all looked good. Then I bought a speedometer on ebay for $50 and installed it and it works great now!!!

This is surprising because my old psom showed none of the defects that other posts had described. (bad soldering, blown capictors, etc.)

My only problem now is my odometer went from 85k to 285k, but I can live with that as long as it works!

Thanks for everyone's help on this.