I have a '92YJ also and couldn't find a manual anywhere with the type of diagram that looked like the one I had. Evidently in '92 they changed the vacuum switch to only two ports on top instead of three. Only one has vacuum at a time, to either engage or disengage. Put the entire jeep up on jack stands or lift and switch into 4WD and see if the vacuum is present in each. If the vacuum is there respectively you may have to buy a new vac switch but don't go to the dealer you can get the exact same one (Dana Spicer) from 4WD Hardware for about $100 bucks cheaper.
Peace River Jeepers
[COLOR=blue]Blue Jeep Club Member #23[/COLOR]
'92 [COLOR=blue]Blue[/COLOR] YJ 4.0 HO, 5spd.
'04 [COLOR=silver]Bright Silver[/COLOR] Liberty Sport 4X4 3.7L Stock for now
What do a Divorce in Alabama, A Tornado in Kansas and a Hurricane in Florida all have in common?.....No matter what someone is fixin' to lose a trailer