13 speed splitter/speedometer relationship

To all my mechanics, I just happened to notice because I bumped it with my leg but I have a 2000 Pete 379. If I’m sitting still with the truck idling and i flip the shifter into high range then move the spitter from direct to overdrive it will make the speedometer go from 0 to 85 and back to 0. Same when you move it back from overdrive to direct. It will also throw my ELOG into driving. Can some explain the relationship between this and what maybe can causing this.

 

Grinding during range shifts? I'd think a pad missing off a hi/low synchronizer might spin it.

Actually, a loose yoke nut is more likely, causing your pulse wheel to spin.

Seen it kick out high idle before due to vibration.

 

I’ll double check everything but I haven’t noticed anything out of the ordinary as far coming out of gear/grinding or anything like that

 

Like the doctor said.

“Well, don’t do that “

 

Hahahaha.. yeah let me just make a note to myself

 

Speedometer works off a sensor counting cogs on the output shaft when they go by. The gear teeth in modern transmissions are cut at an angle. When you split or change ranges that causes the shafts to turn a little and probably rebound at the end. The cog moving back and forth at the sensor causes the reading which is normal.