What does this knob do?

[linebacker]

Whatever you do, don't switch it to the on position while doing 80mph on the interstate.

 

[SafeCracka]

Electronic locker

Agreed

 

[Lockout]

Locks the axles so they turn together

When off only one wheel spins

On both spins

 

[rOmiLaYu]

Traction control. Turn it on and you should get a warning light on the dash

No, it's not TCS, that's on the other side of the cluster.

 

[harrycalahan]

Its pretty obvious it turns the truck off and on.

 

[Lockout]

Whatever you do, don't switch it to the on position while doing 80mph on the interstate.

it will not work unless stopped

 

[rOmiLaYu]

Locks the axles so they turn together

When off only one wheel spins

On both spins

Ahh...limited slip differential makes a lot more sense now. So it basically engages positraction?

 

[CliffB]

Electronic Locking Differential E163170 Illuminates when using the electronic locking differential.

 

[3clicks_Off]

The reason Ford decided to show the wheels turn right on the knob is because all the rednecks would think its NASCAR mode if it showed Left Turns only

 

[JamesG]

If I had one, would I be asking the peanut gallery?

Mebe you just don't have anyone to talk to?

it will not work unless stopped

Hopefully.