Yesterday I bought a 1999 F-350 w/V-10 and automatic trans. Today I was leaving the grocery market, traveling up a slight incline and as the truck shifted from 1st to 2nd it lurched forward. I looked at the instrument panel and the speedometer wasn't registering (0). When it shifted up from 2nd it also lurched. When I got home when I slowed to turn into drive it was like it downshifted early, slowing at each downshift as if you were pulling it down a gear earlier than you should. Is the tranny now a boat anchor??? I bought the truck from a lot and have a Guardian 90 day warranty which should cover it (?). Anyone know just what happened?

 

Is the ABS light on?

If the speedo wasn't registering and you were moving, that's a definite indicator that the speed sensor on the rear-end is out. There is a sensor on the top of the pumpkin, it feeds the speedo and ABS.

They're cheap, and a known problem.

If the speedo was at 0 and you were moving, that's gotta be it (or the wiring)...

 

The ABS light is not on...I am more concerned with the tranny acting the way it is. Seems like the two are related. Thanks for the reply!

 

After my last post I took the truck to work (I work in the woods behind the house) and it seemed all right so I got on the hard road and drove a couple mile. NO PROBLEM!!!???

The speedometer worked and it shifted fine. This would lead you to think electrical problem, telling it when to shift.

I have a tow job Tuesday morning and I am thinking I will go ahead and give it a shot.

Anyone have similar problem?

 

Still sounds like the speed sensor on top of the rear end. With it giving bad readings, the tranny will shift weird, and the speedo will read wrong.

It may or may not light the ABS light - is the "overdrive off" light on the gear selector blinking? Make sure the light actually works and hit the button to take it out of O/D - it'll light amber.

 

I agree replace the sensor to be sure..$20.00 and ten minutes.

 

Did the O/D light start to flash? IF so it will kick out a falut code. The PCM monitors
engine rpm and vehilce speed, if it detects slippage it up's the line pressure to try
and compensate. If you speed sensor failed that will probably account for the hard
shift. I would pull codes just to check.

 

I agree with 99 and the other poster change or clean the sensor on top of the rear diff.
its a common problem trust us we've seen it alot before .
also you may have ran over something that caught the wiring while working in the woods.
Rich