i have a 2000 f150 4x4 7700 and when im driving sometimes the speedometer will bounce and jitter around or almost when accelerating almost tick like a clock. its not smooth when accelerating. when i put on the cruise control the speed stays the same but the speedometer still dances around. the truck shifts and drives fine but it's really getting annoying now. how can i fix this and make it smooth and accurate again?

thanks in advance

 

This is strange. I believe your truck uses a sender (on the rear axle?) to electrically drive the speedometer. I imagine if the teeth in the gear on this thing were damaged, it would give the symptoms you describe. But, the PCM has to get a speed reading somehow too if it controls the cruise control and to make shifts occur at the proper point. So, where does it get its information from? Is there an additional sender/sensor?

I'm asking this question because I don't have any real knowledge of your MY truck, but maybe my thoughts will trigger a response from someone who DOES have that knowledge.

Wish I could be more help.

- Jack

 

Sounds like a cluster problem, with the CC still working.

The VSS feeds the servo. So with the CC working correctly, all that is good.

You can get a cluster from a bone yard, and swap the HEC from yours to the new one. this will transfer the millage and the PATS info.