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Discussion Starter #1
Hi, I have a 2005 GMC Sierra, the indicator lights work on the 4wd selector switch, when I switch into 4HI the light indicates I am in 4HI but it seems like the transfer case is slipping?? I press on the throttle and I need a lot of throttle to get moving and if it moves it jumps.. any ideas what could be causing this? Bad transfer case? Bad encoder motor? Bad actuator? I have no clue.. any help is appreciated, thanks in advance!!
 

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I would say your in 4 wheel drive low gear.

Are you pushing the correct button?
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Steering straight, soft surface?
 

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Check your drive train fluids. if the 4wd service lamp is on then an electrical issue..have a person create video when in 4WD on snow .. all front/rear wheels will spin.. if the rear diff eaton locker locks then the diff will pop in when the one rear wheel spins , then the both rear wheels lock together and cause a pop..
 

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Still think your in 4 low, have you tried the 4 low position for a comparison?
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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I don't think he's in 4Lo. Or...not completely. That would be jerky with any throttle, not a lot.

Once the vehicle falls into 4wd, does it stay there and act normal, or is it slippy and jerky forever?

Does the vehicle behave normal in 2wd? I believe this is when GM went back to front shafts that don't spin 100% of the time. Maybe front U-joints are seized?
 

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Jacob, my thoughts are:
-he says the engine revs in 4wd
-he says the truck jerks when in 4wd
-he says the truck won't go into 4low
-he also says 2wd works fine.

I have never taken a transfer case apart; but I expect there is always a direct connection between the input shaft and the output, nothing that would let the transfer case slip; therefore, if the rpms go up the gearing must have changed.

I do know when a truck is in 4low, there is a lot of jerking if the gas pedal isn't operated smoothly.

So OP, if the rpms are high and the wheels are turning slowly, suspect that the transfer case has moved into 4 low.
 

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Discussion Starter #11
Ray, yup it’s fine in 2wd but when I shift into 4HI it jerks and sounds like squealing brake discs as best as I can describe it??? 4LO will just not engage the lights on my switch will blink and I can hear the motor do clunking sound on the transfer case but the the light on the switch goes back into 4HI position and same thing.. thanks guys
 

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Discussion Starter #12
I have to give the truck a lot of throttle to get moving then the squealing sound happens and the truck is jumping around, I also have tried to go in reverse gear the other day and it was just doing a grinding noise and not going in reverse... once switching into 4HI reverse is back and switching back to 2wd my reverse works fine again.. almost like my transmission is going but it shifts perfectly good in drive. This only happened to me 2-3 times.
 

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I would say, from your above description, that a rebuild of the transfer case is in your near future.
 

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I was going to say I don't know because the costs in Canada are probably different than the US prices; but I see your also in Canada.

I'd start with a tear down to see if I could rebuild it myself.
If I couldn't rebuild, I'd look for one at a junkyard, then a reman and then a new one
 

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Your truck came with a transfer case that has a lubrication pump that can fail due to loss of fluid from the pump housing tabs wearing down and putting a hole in the front case half.
Jcat suggested you check the fluid level.
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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There is a chain, orbital gear, or belt in there. Might be broke, misaligned, something.

I'm learning much from the Google, having also never been inside a transfer case.
 

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Google is not our friend though.
 

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There is also a range selector located at the input planetary gear set that moves in 3 positions that connect the input and output shafts. The range selector is splined to the output shaft.
  • Range position 1 is 2WD and 4HI. In 2WD, the input and output shafts are in direct drive mode and the chain and sprockets are not engaged. In 4HI, the input and output shafts are in direct drive mode but the chain and sprockets are engaged transferring power to front wheels.
  • Range position 2 is neutral
  • Range position 3 is 4LO. In 4LO the the input and output shafts are in speed reduction mode dependent on planet gear set ratio and the chain and sprockets are also engaged to transfer power to front wheels.

I suspect the range selector splines is stuck in 4LO (buggered splines from engaging not in neutral) or splines are stripped causing the truck to jump when it catches.
 
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