2nd Gen Non-Engine/Transmission no 4 wheel drive

[TMaki]

what puts the front end in 4 wheel i went to use 4 wheel today and it didnt work. the transfer case works but 4 wheel doest. have lotsa snow on the way in mn. im going to need it i did not try 4 wheel since i9 bought it

 

[bighammer]

The front axle disconnect is a little thing on the right axle tube. It has 2 vaccuum hoses from the transfer case that make it connect or disconnect.

The transfer case has a "vaccuum switch" that changes which line has vaccuum when you shift to fwd.

First check that you have vaccuum going to the transfer case. There is a T fitting (really more of an "F" if I remember right) on the firewall near the 2 relays that controll the shutoff solenoid. Shouldn't be too hard to find the one that goes to the transfer case unless it's disconnected or something.

I think the part on the transfer case is often t he culprit, so in a pinch, you could extend the hoses from the axle and connect the proper one there. (sort of a pop the hood to change)

 

[klaybus]

what puts the front end in 4 wheel i went to use 4 wheel today and it didnt work. the transfer case works but 4 wheel doest. have lotsa snow on the way in mn. im going to need it i did not try 4 wheel since i9 bought it

Like said above, check the vacuum lines on the front axle. Also check on top of the transfer case at the vacuum switch. I had a problem with mine & it was a line that was pinched not allowing vacuum to the vacuum motor attached at the front axle.

To test the vacuum motor I hooked up a small rubber hose to a Tee that was plugged off at the firewall. There are (2) lines that hook up at the differential. (Red & Black) I don't recall which engages & disengages but I think Black engages it. Run a vacuum line to one of the ports at the front axle (engine running) & with the transfer case shifted to 4WD the light should illuminate. If the 4WD light does not come on, put the vacuum on the other port. If your 4WD light comes on you know you either have a vacuum leak or the vacuum switch on top of the transfer case is bad. I replaced my switch before finding the leak. (pinched line) The switch at the dealer was only $36 or so...

Keep us posted.



Clay

 

[TMaki]

thanks ill give it a try

 

[JDKammin]

What I have done when I know vacuum is OK, is remove the four 1/4" bolts that hold the disconnect in the axle. Start the truck up, shift the transfer case lever into 4WD. The fork should move to the left. Shift back into 2WD and fork should move to the right. Make sure there are plastic wear pads at the ends of the fork. If these are missing, your shift collar will not engage completely. If your fork does not move, your vacuum disconnect unit is bad. You may want to install the posi cable and not have this problem again.

 

[bsappington]

The same thing happened to friend. It turned out that when I looked under the truck it was packed with snow. When we dug all of the snow out we had found that the snow had removed the lines from the transfercase switch. We put them back on and pproblem solved.



I hope this helps,



Ben

 

[DBohl]

I had this happen to me also, turned out to be a hole in the vacuum line right on top of the transfer case. It had rubbed against the bottom of the cab. As mentioned before, check for vacuum line leaks before replacing anything.

 

[RDelissen]

more than likely the vacuum hose at the axle end



It might also cause 'flickering' of the 4wd light after disengaging 4wd, when not connected properly

 

[TMaki]

that is another prob the light doesnt work . i just about got it shoveled out from the storm so ill look at vacaum lines

 

[TMaki]

ok i finally got to it and i found a vacum line coming from the transfer case that goes no where. there is a grey hose and a green hose coming up the fire wall from transfer case the green one is not hooked up. where does the green hose go?

 

[klaybus]

I just went out to my truck & looked under the hood... . What side of the truck is the green vac. line coming up on? I found a few vacuum lines but not a green one. Every vac. line that comes up to the firewall plugs into a tee...



Clay

 

[TMaki]

it comes up the drivers side towards the middle of the firewall with the grey one that goes to the tee. . i tried plugging the green one into the vac tee and the light comes on in 2 wheel drive and goes out in 4 wheel?

 

[DieselDoghouse]

WHOA! you swapped the two lines and the function reversed?? Then what you have is probably the vent line - it admits air to ALLOW the vacuum line to draw the diaphragm in the shift motor left or right. When you swapped them you reversed the function of the vacuum switch on the transfer case. I'll try to explain:



2WD = vacuum into right chamber, AIR into left chamber - shift moves out axle.



4WD = vacuum into left chamber, AIR into right chamber - shift moves inboard to couple axle shafts.



when you swapped those lines you reversed the flow routed by the vacuum switch and saw what you did…

 

[TMaki]

does that mean that i have a vacuam leak in the vacuam supply line?