No speedo and OD light flashing problem
I had this problem last year. I fixed it with a new speedo sensor in the rearend.
Now its back again.
-Check the fuse.
-Speedo sensor is good, I swaped it out with my work truck one.
-Check for codes and nothing is showing.
-Traced the wires from the abs modual to senors all is good.
I have to check the trans sensor.
The only other change to the truck was the replacement of the alternator, I don't know if this would affect anything.
Any help would be great, its already cost me a speeding ticket.