differential type and amount? should be premium demnad drive LT or PLUS, 9.3oz. take an ohm meter and put the leads one on each side of the plug coming from the diff. there should be around 24 ohms. also use a volt meter and check your battery, it takes good voltage to run the diff. the sprague could just have a hair line crack and cause it not to work. also how did the rollers look? just something to look into?
Mine wouldn't work one night when I tried to drive back out of a ditch I was stuck in. The AWD light would be on but no AWD. When I did get out, I found that the AWD wire connector (roundabout where the brake fluid reservoir is) became un-snapped a bit. Unplugged it, plugged it back in and all was and still is good.
Unplug it from there and snap it back in and see if it changes anything. Also, would be a good idea to spray it with non-lubricating electrical contact cleaner.
i chased a problem with mine for a while..turned out the connector would lose connection if you wiggled it around.i cut out the connector and replaced it with one i got at radio shack for about 3 bucks.its fixed now........also,ive had my vent hose come off the front end and get a little water in it and it wont work.it doesnt take much of any contamination of the front end fluid to get it not to work correctly............