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Discussion Starter · #1 ·
Hi,
My Tb is a 2005 with 4wd drive, it has about 80K Miles on it.
During an offroad drive one of my rear wheels was stuck in a mud hole and i tried engaging my 4wd in both Hi and Low but i was unable to get my self out.
From that day i suspected that my 4wd isnt working, there is no 4wd service light on and everything looks fine, In 4wd low i can feel my TB is locked, i tested it in a high slope and turned on 4wd low and the car stood still (it reversed back in a very very slow speed but i think its normal since the slope was very high).
I noticed when i turn on 4wd in Hi, i hear every few minutes a clicking sound from the front of the car and in hard right turns i hear alot of clicking sound.
I jacked the car from the front and lifted both front wheels in the air and pulled my parking brakes to prevent rear wheels from moving, then i switched to 4wd in both hi and low and pressed the gas a little to see if the front wheels are moving but they didn't move.
My outer CV joints looks good but didnt check the inner ones.
I am suspecting that the problem is with the inner cv joint or the cv axle disconnect,
does anyone have an idea about the problem?
 

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Discussion Starter · #3 ·

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2002 chevy trailblazer_lt
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Engine off, transmission in Park.

The concept is this... With the transmission in Park the transmission output shaft cannot turn. Now with the transfer case in 4hi then the internals of the transfer case are connected to the transmission and thus they also cannot turn. When the 4WD switch is not in 2Hi then the front axle disconnect has locked the front left and front right cv shafts (axles) together such that one side cannot turn without the other side, or the front driveshaft also turning due to them all being geared together in the front differential.. So with just one wheel off the ground, and all those other components locked together, the wheel should also be locked, allowing just the slightest rotation that takes up the slack in the geartrain.

If the wheel does rotate then something is not locking properly and the rest of the procedure serves to pinpoint just where is that failure.
 

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jacked the car from the front and lifted both front wheels in the air and pulled my parking brakes to prevent rear wheels from moving, then i switched to 4wd in both hi and low and pressed the gas a little to see if the front wheels are moving but they didn't move.
Correct. They cannot move because in 4hi and 4 lo they are locked together in the transfer case. At least one front and one rear must be able to rotate.
 

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Discussion Starter · #6 · (Edited)
Engine off, transmission in Park.

The concept is this... With the transmission in Park the transmission output shaft cannot turn. Now with the transfer case in 4hi then the internals of the transfer case are connected to the transmission and thus they also cannot turn. When the 4WD switch is not in 2Hi then the front axle disconnect has locked the front left and front right cv shafts (axles) together such that one side cannot turn without the other side, or the front driveshaft also turning due to them all being geared together in the front differential.. So with just one wheel off the ground, and all those other components locked together, the wheel should also be locked, allowing just the slightest rotation that takes up the slack in the geartrain.

If the wheel does rotate then something is not locking properly and the rest of the procedure serves to pinpoint just where is that failure.
First i would like to thank you for the help,
I followed the guide and it led me to the 4wd disconnect, so i will replace it and check if things works.
Also i did few other tests just to be sure, i jacked the whole car and put the car in 4hi and one of the rear wheels kept it on ground. Then i turned on the car with minimal gas on Drive and the rear wheel that is above ground turned but the front wheels didn't turn, and the Rear Prop Shaft Turned and the Front Prop shaft turned. This made me sure that the problem is either from the front differential or the 4wd disconnect but according to the guide its the 4wd disconnect so i will check and see what happens.
 
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