My Od light was flashing too. I serviced the rear diff and cleaned off the sensor. Still did it.


So I noticed that it would blow the fuse when I turned on the AC. I looked under the hood and the wires coming from the plug on the compressor were touching some metal. Then I noticed a burn mark on the metal, so I guess it was shorting out right there. Moved the wires, replaced the fuse without another 10amp and drove it all day with no problems. Everything works, abs light is off, ac works, all the symptoms.

 

Sounds like a PSOM issue (programmable speedometer/odometer module). PSOM is a small computer chip that sits behind the speedo... signal comes from VSS to PSOM, PSOM sends info to trans and engine based on signal from VSS. Bad PSOM = bouncy speedo, erratic shifting, no cruise, and if left long enough a toasted trans (tranny is going nuts trying to figure out what to do while the speedo is bouncing).
mx510- glad you found the problem.

 

Glad you found the problem. Thanks for sharing what the problem was. I think I might have jiggled some wires under the hood while I checked the oil. Maybe I fixed mine to.

 

BigCab,

Did you find a solutions to your VSS problems you first posted about. I too am having along the same difficulties...
Rear end checks out, transmission checks out, replaced VSS at least 3 times in the last month, replaced pigtail for VSS.
Speedometer still jumping eratically, automatic trans shifting out of gear into neutral as you r driving. Anyone have a clue as to what to try next, I was told it maybe a instrument cluster or computer, but as of yesterday when I was at Ford, they are no longer making these parts...

 

Can any body help me have a 2003 f350 6.0 4x4.tryed fixing speedometer. Replaced vss on rear end and still no speedometer. Also took out tss and oss sensors cleaned put back in.now truck wont start.any clues why thanks