I don't know if anybody can help me or not. I have a 1999 ford f350 diesel, sometimes when I start up and get moving the speedometer will not register and the od light will start blinking. I'll stop the truck and turn the engine off and then on again and it will be fine. It doesn't happen every time. Someone suggested the vss sensor maybe going bad. Anybody have any thoughts on this. Any help would be appreciated

 

Is it a 99 or an 89 model, if it's a 99 your may what to try the newer vehicle forum here for help. Or you may get lucky and someone on this forum can help.

 

If the O/D light was blinking then the computer has a stored error code, may be worth pulling the code before you throw parts at it.

 

I got a 95 E250 that will do that sometimes-on mine the switch doesn't return to the run mode-I'll just wiggle the key a bit and everything starts working right

 

You may want to try the Super duty and heavy duty forum.

If I remember right your truck may have two speed sensors, one for above 35 mph and one for below 35 mph. Pulling your codes will help on establishing what the issue is, when your OD light is blinking it is a problem on the trans side.