Could Speedometer problems be linked to the ECM??

[JGrefenstette]

My speedometer and odometer have been failing at the same time, off and on for the past few months. since i bought the truck in early may. i have been able to just tap the gear reducer and it would come back on. but a few weeks ago it went out and stayed out. this was just before my ECM went dead. I replaced the ECM to try and solve my charging systems problem. that worked, and the charging system is good again, and the speedometer came back to life after i put the new ecm in the truck. this made me think that the speedometer was possible linked to the ECM going out. i thought that if it was my problem was solved and i have a speedometer again. but yesterday it went out. this was 4 days after driving it with the new ecm. I dont know if its just a coincidence that it came back after the new ecm, or if it was strongly conected.

here are my questions for yall:

Is the speedometer conected to the ecm in any way at all???

If so, does the speedometer dying again mean that my ecm is getting ready to go bad again, and its just eleminating the weekest link first?

If not, why would it come on emidiatly after i replaced the ecm?

(one last thing, when it went out, it was a few minutes after leaving a treefarm that i work on. i hadnt taken the truck there since the new ecm, and i was wondering if all the bouncing could have contributed to the failure of the speedometer agian. i left the farm and it worked fine while i drove 1-2 miles to the gas station, i parked, let it idle for 5-10 minutes while i filled two gas cans, then when i pulled back out on the road it wasnt working?)

any thoughts or comments would be more than appreciated!
thanks for taking the time to read my mess of thoughts and concerns.