Ok how it started is I would turn the ESOF switch to 4X4 H and the front hubs would not engage but the defroster would come on... Seem like a vacume leak but waite so durring the trouble shotting I disconected both of the vacume lines at the hubs and cap them off with plugs turned the switch and still went to defrost... I looked around and around for any highly vissable signs but nothing so i traced the vacume lines back to the pluse vacume hub lock valve disconected the out side (to the hubs) and pulled a vacume on it..The lines checked ok this got me wondering so I hooked my vacum gauge to the PVHL valve and I had no vacume indicated but on the other side (to the resavor) itobviously did hav a vacume.. I got my meter out and had 12 +/- only at the center lead..At this time every thing is backe hooked up like factory and when I switch to 4X4 my ac doesn't go to defrost but the hubs don't loke in the tranfer case does but not the hubs. Hubs work fine in manual did all the final checks prio to postin with all fore tires off the ground and the truck tied down just to be certin. My quiestion are the other two wires on the Pluse valve I am sure one is a grould and the other is what and where does it get it's power from (if it has power)? the other quiestion is how do you test the pluse valve itself and how much is a new one or is there a history of these valves going bad most or the reads are about bad vacume pumps or lines.
Am i missing any thing? Ant thing else I can do befor I start spending money?

 

up-date i woke up this morning started the truck and noticed that the 4x4 indicator light was on I looked at the ESOF switch and it was in the 2wd position drove the truck and confirmed that it was in 4wd and not only 4wd but 4 LOW. I went under the truck unpluged (hopping it would fail to 2wd) the tranfercase shift motor but it remaind in 4wd with the light on. I then disconected the dash and unpluged the ESOF switch but the truck remain in 4wd. The truck was never moved froom trouble shotting to when I test drove it yesterday after rotating the tires all I did was look for a vacume leak and switch the switch a few times looking for voltage at the pulse valve. Any help would be greatly appreciated thanks in advance.

 

Another up date to the up date I prety much got PO at the truck so I went under witk a hammer and raped on the shift solionid T-case not stuck in 4low any more. Still have the pulse valve problem though. If anyone has a wirring digram for the pluse valve or just knows what wires should/shouldn't have power