2ktransam

iTrader: (12)

Why would my log show my MPH raise when I am brake stalling my truck in 4wd even though I am not moving? When I brake stall my truck in 4wd it will show that I am moving for a second and then it goes back down to zero but the truck never moves an inch.

gtosilverado

iTrader: (3)

i think thats normal ???? when i have mine on park, and i step on the gas, and i go past 4k rpms, the MPH needle starts moving,....

hog

Yes thats normal to a degree. Its the RF interference from the ignition acting on the VSS signals from the PCM to the speedo cluster.
These wires are usually shieded but can still be affected. This is why when wiring up the speedo to shield them.

I think in 2ktransam's case the VSS reluctor might give the VSS a count or 2 due to some drivetrain slop?
It might also simply be some RF interference.

peace
Hog