Front wheels won’t turn when in 4WD

[DrDaveMD89]

Problem is as stated in the title. Got stuck in the mud and the front wheels wouldn’t budge but the rears would spin like no tomorrow. I’m able to engage 4hi and 4lo, no lights are flashing and no service 4x4 lights either. I can hear it engage when in 4hi and I can definitely hear it and feel it when it’s in 4lo. Seemed to have worked during the winter but I had suspected maybe something was up at that time as well. I only ever use my 4wd when I need it otherwise I stay in 2wd.

 

I don’t wrench a lot but I know how to do basic maintenance like oil changes, spark plugs, oil pressure sensors and even some exhaust work but i wouldn’t call myself exactly mechanically savvy.

 

The truck is a 2011 Silverado 1500 5.3 LT Z71 crew cab. 

 

Please help and thanks in advance!!

[EastTNChevy]

Do you ever put it in 4 hi and drive it a short distance to keep everything free like the manual says?


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[DrDaveMD89]

51 minutes ago, EastTNChevy said:

Do you ever put it in 4 hi and drive it a short distance to keep everything free like the manual says?


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I don’t recall reading that in the manual but I’ll take your word for it. I guess I haven’t done that

[davester]

Put it in 4hi (so it's engaged, if you've got an electric 4wd setup), and the transmission in park.

Lift one front wheel off the ground and try to spin it.

 

If you can't spin it, then you are in 4wd, and it's working.

 

If you can spin it, look and see if the front driveshaft spins when you spin the front wheel.  You might also want to physically hold the driveshaft to confirm that rotating the wheel positively rotates the front driveshaft or not.

If it does spin, then most likely the chain in the transfer case is broken (but it could be something else, like the shifting fork is busted, or the electric shift motor isn't working right)

If it doesn't spin the front driveshaft, then something is wrong with the front diff, like the electric solenoid for locking the front axle isn't working, or the gear that locks the axle together is broken, or the passenger side stub axle (inside the diff) is broken (these are fairly common failures), or the front diff itself has turned to many little metal bits inside (less common).

[DrDaveMD89]

9 hours ago, davester said:

Put it in 4hi (so it's engaged, if you've got an electric 4wd setup), and the transmission in park.

Lift one front wheel off the ground and try to spin it.

 

If you can't spin it, then you are in 4wd, and it's working.

 

If you can spin it, look and see if the front driveshaft spins when you spin the front wheel.  You might also want to physically hold the driveshaft to confirm that rotating the wheel positively rotates the front driveshaft or not.

If it does spin, then most likely the chain in the transfer case is broken (but it could be something else, like the shifting fork is busted, or the electric shift motor isn't working right)

If it doesn't spin the front driveshaft, then something is wrong with the front diff, like the electric solenoid for locking the front axle isn't working, or the gear that locks the axle together is broken, or the passenger side stub axle (inside the diff) is broken (these are fairly common failures), or the front diff itself has turned to many little metal bits inside (less common).

Wheels spin but the front drive shaft does not. Kinda bummed to find that. Could it be the actuator??

[DrDaveMD89]

Update- actuator works as it should 

[davester]

If the actuator moves in and out appropriately, then, most likely it's the sliding gear the actuator moves, to connect the passenger side axle to the differential is broken, next most likely is the passenger side axle, then (least likely) something scrambled the actual diff itself.

 

The first two things are straightforward to fix, mostly just bolts and some c-clips to take it apart and put it back together, and you don't need to drop the diff to do it (as the diff splits on the passenger side by the actuator, and you can just replace the broken bits and stuff it back together.

 

If the diff itself is scrambled, I would suggest just getting a used one from a junkyard, as it's fairly expensive to rebuild the diff, and they rarely fail.

 

Sign up for the full-service manual at any number of online sites, like alldatadiy.com, helminc.com I think, and others, to find out exactly what you have to do, to see if you are comfortable with doing the work yourself, if you want to.

[DrDaveMD89]

11 minutes ago, davester said:

If the actuator moves in and out appropriately, then, most likely it's the sliding gear the actuator moves, to connect the passenger side axle to the differential is broken, next most likely is the passenger side axle, then (least likely) something scrambled the actual diff itself.

 

The first two things are straightforward to fix, mostly just bolts and some c-clips to take it apart and put it back together, and you don't need to drop the diff to do it (as the diff splits on the passenger side by the actuator, and you can just replace the broken bits and stuff it back together.

 

If the diff itself is scrambled, I would suggest just getting a used one from a junkyard, as it's fairly expensive to rebuild the diff, and they rarely fail.

 

Sign up for the full-service manual at any number of online sites, like alldatadiy.com, helminc.com I think, and others, to find out exactly what you have to do, to see if you are comfortable with doing the work yourself, if you want to.

I will look into those diy manuals. Thanks!