i have a 2005 silverado 4x4 and it has a auto 4x4 button how does this work and what speed can you drive in ti

 

Auto 4x4 basically puts your truck in ready 4x4 mode.
It will automatically go into 4x4 when your transmission senses any wheel slippage.
You can leave your truck in Auto 4x4 mode all day long.
It's Full Time 4x4 you don't want to use in dry conditions.4x4 is for wet slippery conditions.

 

if you plan to run in auto 4wd all the time, make sure you have 4 matched tires of the same brand, size and circumference.

 

For the same reason, there are no speed limits.