4x4 won't work

05chevy

05chevy

gear head
Joined
Jul 17, 2010
Messages
635
Hey guys my 4x4 won't work in high or low. What could be wrong with it. I don't know much about how the 4x4 works on this that well. Do the hubs lock in by vacuum. Any help would be appreciated.
 
I would pull the hoses off of the vacuum canister on the front axle. Check and see if you are getting any vacuum on one of the hoses, when 4x4 is engaged. Put a finger on the end of the hoses to determine if you have vacuum. If you have vacuum, remove the 4 bolts that hold the shift mechanism onto the front axle. Plug the vacuum hoses back up and have someone shift in and out of 4x4. The shift fork should be moving back and forth. Make sure the pads are at each end of the shift fork. If the fork does not slide, your vacuum canister is bad. If you do not have vacuum to the front axle, check for bad hoses and steel lines from the front axle back to the transfer case. There is a vacuum switch on top of the transfer case. You can pull the plug off of the top of the switch and see if you are getting vaccum from the motor. If you are not gettting vacuum, there is a hose that hooks up to a tee fitting that feeds vacuum to the transfer case switch. The tee is located near the firewall, just inside the master cylinder.
 
Ok thank u ill give it a try

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I had a vacuum line pop off last year running through some snow. Easiest to check too.
 
I just replaced a vacuum line. It had worn a hole by where it come out of the vacuum pump.
 
Ok I'm getting vacum from the motor to the back of the transfer case but get nothing after that there is a red and black line that runs to the steel line infront on thr botton on the case I can get no vacum there the black on has oil in it and the red one has nothing

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could be that the rubber plug is leaking on the switch. mine was so i hooked up the 4 vac lines directly. Also you can take the switch out and blow air through it to see if it works in 2wd the push the ball in to see if air is going through it for 4wd
 
There is a diagram of the lines floating around here or google it it msy help with diagnosing the problem
 
I think I might just buy the bd 2wd low gear kit to just activate the front axle to try to eliminate all the vacuum problems.

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Just take the fork slider piece apart and place some washers between the fork and the housing to hold it over in the engaged position. No more worries about vacuum lines or switches or diaphrams. Just move lever to 4x4 and it works. I've done it to both my trucks.
 
GOT-Torque said:
Just take the fork slider piece apart and place some washers between the fork and the housing to hold it over in the engaged position. No more worries about vacuum lines or switches or diaphrams. Just move lever to 4x4 and it works. I've done it to both my trucks.
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any turning issues on dry pavement?
 
I had a slider that would get stuck in the disengaged position. I just pulled the line that disengaged it and called it good since it was on a puller.
 
no issues what so ever. Didn't notice a drop in mileage either (others felt there would be).

I've had problems with both trucks at one point, and it was always at the most inconvient time so I said the heck with it and locked them both in.
 
OrangeNV said:
any turning issues on dry pavement?
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Doing this would cause some binding when turning on pavement. I installed the posi-lock on my truck and called it a day. Too many people having vacumm issues fro me to want to repair it. Used the posi-lock quite a few times with out any issues. Also like like to put the transfer case in low gear while backing up heavy loads giving me the added feature of 2lo which rocks.
 
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