96 gmc jimmy 4 wheel drive

truck doesnt seem to kick into 4 wheel drive after hitting the push button, i can hear the usuall sound it makes like when its trying to kick in, when i hit the 4low button also the cars lights get really dim and kicks forward or backwards really bad depending on if you put it in drive or reverse. Any ideas?

Jack it up and check friont drive shaft and front axels for locking into 4W.
Post back wich way it goes.

jacked it up, doesnt lock

What part?
Front axel or front drive shaft?
Fuses all good?
Does all shift buttons light up key on bulb check?
Any code with grounding pin 13?
Post back any codes.
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914