No you don't. The VSS doesn't know which way the truck is going, reverse or forward. It registers speed no matter what

 

Real men don't back up they just hit the skinny pedal and charge ahead!

 

yes when I was check VSS in rear axle it act like laser eye on object.

 

I had no idea. I've never noticed the speedos action while reversing. I guess I actually pay attention to where I'm heading while backing up. Go figure huh?

My speedo has that irritating jumping at slow speeds and thinking about it I do remember it jumping while in reverse while testing it after I had attempted cleaning the rear dif sensor. (Didn't fix it)

 

When I was plowing on Sat. night I looked down at the speedo I was around 23mph pretty regularly in reverse.

Reason....designated area I need to push/stack the snow and it's a long parking lot.

 

Unfortunately, my 08 F350 SRW V10 with auto trans only does 0 in reverse.

Only has 18K miles
I was out snow plowing, BOSS V plow, and could not back up,
Reverse felt like a a standard trans with a bad clutch,
engine speed came up, but I was not moving.
I found that if I used the plow to push off the pile, I could get moving and then the trans would catch.

So I drove it to the Dealer last night with the hope it was a bad sensor.
Dealer called first thing this AM
DEAD TRANS!

 

to tell the truth never look at the speedo plowing looking hard at where I am going