front axle stuck in 4wd

i replaced the front axle switch that tells the ABS that the ront axle is engauged. even thought it wasn't in 4X4. so i hooked up a scanner to it and according to the ABS it was in 4X4. so i pulled the plug out of the switch and the computer then said it was out of 4X4. i played with it for prob about 3 hours and nothing seemed to come of it. all i can think of is the the front diff isn't pulling out of 4X4. i know this is a common problem so it prob is. it would also explain the tires wearing fast and the loss in gas mileage. i plan to play with it more tomarrow. heres the thing i do know. no fuses are blown. the transffer case is coming out of 4X4 its just the front axle thats not. vac holds at 20 with the engine off and holds about 20 with it running. i'm going to pull the bat out tomarrow and check the vac switch thats under that switches the diff. anybody delt with this before and any idea what a new vac switch might be?

I'm not going to answer your question. :iceslolan




However I will give you tha address to the best troubleshooting guide that I've found on this subject.
http://www.4x4posi-lok.com/PDFs/TSG_chevyT.pdf

I think that you'll find the info that you need in there

ok. checked it out today. tried it before i did anything and it was still stuck. pulled the batt out and the batt plate out and pulled the vac switch out as well. placed it to the side still hooked up and hooked the batt back up sitting there. started the truck pu and then 4X4 worked fine. pulled in and out no prob. put it all back together and still fine took it for a drive and still no problem. the only thing i can think of is that the tccm might have been confused since the bad switch. it makes sense because if the truck sat over night and i tested it, it would be out of 4X4 but as soon as it started 4X4 it would go. i have noticed that it picks up a little better and the clunk i used to have is now gone. checked fluid in the diff and it was fine. i'm going to test it later this week and see if its still working right.