Speedometer problems....

[quote:bfcf610c15="GaryL"]What could possibly be wrong with the speedometer in a F-150, 4x4, 1995, 351. Speedometer jumps from 20 to 40 regardless of speed. We have changed the cluster in the dash and speed control sensor in the rear end. Traced wires from speed control sensor in the rear end to where it enters the cab and everything checks ok there. Cannot trace from entering cab to cluster...Does this go thru the ABS controller and where can it be found and will this affect the transmission shifting?[/quote:bfcf610c15]
HELLO
CHECK RING GEAR IN THE REAR END
SCAN THE PCM CHECK THE SPEED ON YOUR SCANER
THAT WILL HELP YOU TO PIN POINT THE TROBLE AREA (IF THE SCANER DOING THE SAME THE PROBLEM MAY BE IN THE BACK IF NOT THE YOU GOT A BAD CLUSTER )
GOOD LUCK

We have put 4 different rear ends and 4 different clusters in this truck and it still has the same problem. Refreash my memory about a PCM.....Thanks