4wd problems, need help

[Adirk]

I have a 2004 yukon xl, sle? i believe, but yeah just the plain vortec v8. Anyway, I've noticed recently, whenever im stuck in snow/mud/sand, my rear wheels always spin first. i stuck the rear up on jack stands so the rear wheels could spin freely, and in 4hi and 4low, the front end wasn't able to pull it off the jack stands, only the rear wheels spun in the air which makes me think the 4wd is broken. I replaced the axle actuator and it appeared that that didn't work. i don't have any 4wd error messages and i can hear the transfer case switching, need ideas on what it could be.

 

[large]

I am having the same problem the light says its in 4wd can hear it engage no service 4wd message can put it in 4wd low but the front wheels will not pull have you had any luck finding out what the problem is ?

 

[Adirk]

Sorry, still no luck, I have replaced the front axle actuator and that didnt work, i tested out the power to the actuator and i have 12v and can here it engage when i plug it in, yet still no 4wd, I know it cant be the transfer case because when im in auto 4wheel the front will engage then when the back slip. im thinking like all gms its an electronics issue somewhere

 

[smcnair]

Is your front drive shaft spinning? That is the problem I am having. The actuator engages but I get no power to the front. Put it up on the lift and the drive shaft never moves.

 

[Oobray]

IIRC. The t case is a friction t case. Meaning it has clutches the distribute power between front amd rear. It's possible that's warn. If the front drive shaft isn't spinning then the problem is inside the t case. But you can hear the actuator move even when it's not necesarrily working. I took mine off and cleaned it. There's a series of plastic gears in there that can get gummed up.

 

[Adirk]

I've been a bit absent but i dont think it could be the front drive shaft or the t-case since in auto 4wd, all four wheels will engage if the back isnt quite getting the grip, im not sure at what point that does but ive seen them spin when ive been really stuck.

 

[ccapehartusarmyINF.(ret)]

the last 4wd truck i owned there was either snow and ice on the roadways or they were always wet
the way i always checked was when i engaged 4hi to make sure it was engaged id just put my foot into a little more from a stop and if the rear tires just spun out i was still in 2wd if i was in 4wd the rear tires would spin out at all becuase sometimes it was qwerky i had to drive it for a few miles to get it outta 4hi