Does anyone know where this blue tube goes? These photos are on the passenger side in the engine compartment by the firewall. These are the same colored tubes that connect to the vacuum disconnect and also on the transfer case. Thanx in advance.

If memory serves I think that is a one way vent

It is a vent for the front diff, The round thing on the end is a one way check valve..

So it doesnt connect to anything?

No you diff vent is buy your brake booster,it will have a white cap on it.

Its connected to your TC to engade the front axle when you put it in 4X4

Ok then so does this end of the blue line connect to anything?

No

Dang. Ok. Thank you. Do you have any ideas then why my 4WD wont work? I have an NP231 transfer case. When I move the lever to go into 4 hi/lo I get nothing, nothing engaging, no front wheels grabbing. Any ideas?

anyone.......well it is almost 11pm

I take it you have jacked up one front wheel and checked to make sure the light bulb isn't out. Generally, the culprit is the vacuum diaphragm on the axle disconnect. They are replaceable or you can opt for a more expensive cable operated disconnect. Another option is to take it apart and put some washers in so that it is connected all the time.