I have a 1987 s10 blazer 2.8L. I have the shift lever for the 4x4 on the floor. (not push button) When i shift into 4wd hi the light comes on but does not engage the 4wd. then i try shifting lower to neutral, then to 4wd lo and hear a grinding noise then it feels/sounds like it shifted into 4wd. but still does not engage the front axle. I was wondering if anyone could help me please.
Thank you
rich

Does front drive shaft engage in 4W?
If so check front actuator for engaging front axel?
Got good vacuum to actuator?

This link may help.
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914