Ok, I've been reading everything I can on hear about our 4wd system but I'm not 100% sure I found exactly what I need.

Here's what is going on. With the truck up on a lift and all 4 wheels off the ground if it's in 4wd 3 of the 4 wheels spin fine. The drivers side front does not. It turns as though it's locked in but it's turning slower than the rest. I can actually stop it with my bare hands. Also the 4x4 light will not light up. Their isn't any grinding sound at all. I keep thinking it's a vacum issue but something doesn't seem to add up. To me if it was only partially locked in it should be grinding? Maybe it's a combination of a vacum leak and a busted up IWE.

Any help would be appreciated!
Thanks!

 

Just so we are on the same page - the front diff is an open diff, and you can stop one wheel from turning. Stop the passenger side wheel and the driver's side should turn. If the halfshaft turns but the wheel doesn't, then the IWE is not locked in.

 

yes, it is an open diff. I'll check to see if the halfshaft is still moving. thanks. I was just shocked that i could stop a moving wheel with my hands without much trouble at all.

 

bump
if anyone else has any advice that would be great! It's cold out so the less time I take diagnosing the better.

 

Manual or electric shift for 4x4? If electric (switch instead of floor shifter), try tapping on the shift motor (on the transfer case) with a hammer handle.

A vacuum leak would would not normally prevent the 4WD from engaging... The infamous "grinding" is usually from not enough vacuum to fully DISengage the IWE.

 

Electric...if the shift motor wasn't working I wouldn't see the front wheels turning would I?
Thanks