Another 4wd prob

I have a 2000 Zr2, 3 button 4wd switch (4 hi, lo and 2 hi)...The light on the switch when I push 4hi, lo or 2hi does what it supposed to, and I can hear a clank from the transfer case as if it went into gear but only the rear tires are spinning in the snow....I had a friend use my truck to move (atleast it wasnt me right) and got it back, was in 4hi, it was dry out...he drove atleast 20-30 miles and was smoking, couldnt tell where it was coming from seemed like the engine bay but it was bad and I was pissd...Im sure this has something to do with it...I don't really understand how the 4wd works in this truck...I have a diagnostic sheet the dealer sent me on what the voltages should be reading that the case but I don't think its the swich....??

Also, my rear diff doesn't lock, a mechaninc friend said to add friction modifier to it, I had flushed it, but it never seemed to work anyways for me before...do you think the friction moddifier will do the trick??

Thanks for the help!

You need to find out where that smoking was from.

What transfer case does it have?

Is front axel locking in?

If it does not have a 236 you can get codes by grounding pin 13 on diagnostic connector plug.

If a 236 you will need a transfer case capable scanner to test or get codes.

Post back any codes.

The G80 (posi) rear end in these trucks do not use friction modifier. It will not help. The differential most likely needs an overhaul.

236 transfer case is the one with the 4 button controller. The 3 button is more likely a 233 or 231.

It's not throwing any codes, I have a matco proscanner doesn't seem to connect to the transfer case, grounded pin 13, didn't flash anything....
I have a feeling it was the front diff smoking, maybe through the vent on it running into the engin bay?? I didn't make it to work today due to the 18 inches of snow we got last night...lol, ugh... :disappoin
I'll yank the plugs on the diffs and check fluid hopefully tomorrow, and guess I'll return the friction modifier...don't know what else I could use that on other than my tires right about now....
Thank you guys for the help, the G80 seems nice looking at the vids on youtube...wish it would work....

What transfer case does it hace?

I believe its a 233 but how do I tell? The transfer case is locking the front drive shaft so I believe it something with the front diff...?? Does that vacuum system deal with the front diff at all?

Check the actuator under the battery.
See if it is pulling the cable to front axle to lock it in.

Read this link
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914

Check the actuator under the battery.
See if it is pulling the cable to front axle to lock it in.

Read this link
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914