I have a 2007 GMC Yukon SLT, I haven't had one problem with this vehicle. Until I went out one morning to go to work and it wouldn't go into reverse. It sounds like its full of Steel marbles in reverse and in neutral it goes right into drive but it won't shift up when driven. But my info center says to repair traction control and to services 4x4 also my 4 wheel drive **** on the dash has the 2 wheel light on and the auto light is also on and the 4 high is flashing and nothing changes when I turn the ****. I have a buddy who said he had the same problem in his 07 Silverado it turned out to be a plug was broken on his transfer case. I can't find any n plugs. Any ideas would be appreciated, thank you!

 

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It sounds like a transfer case or wiring issue. Check the plug and wiring on the transfer case—these often break or corrode on GM trucks. Also, check the fluid levels and scan for codes. If wiring looks fine, the encoder motor or sensor on the transfer case might be failing.

 

Thank you I'll check those in the morning. Someone just mentioned the actuator on the transfer case. They said it maybe stuck between 4 and 2 wheel drive. But im not sure if it would sound as it does in reverse and neutral, it sounds like there's a bunch of loose metal in there rattling around and doesn't move at all.

 

Actuator Issue

• The transfer case actuator is responsible for shifting between 2WD and 4WD.
  
• If it’s stuck, the vehicle might not engage 4WD properly, or you could see a warning light.
  
• Usually, a stuck actuator won’t make a loud rattling metal sound inside the transfer case. It might make a clicking sound or fail to shift.
  

Rattling / Loose Metal Sound

• A “bunch of loose metal rattling” inside a transfer case is more likely to indicate:
  
  • Worn or broken gears
    
  • Worn bearings
    
  • Metal debris from previous internal damage
    
• The fact that it sounds the same in Reverse and Neutral suggests that the noise is coming from inside the transfer case itself, not from the drivetrain components that only engage in motion (like differential or driveshafts).
  

What to do next

1. Check fluid — Low or contaminated transfer case fluid can cause internal noise and accelerate damage.
   
2. Inspect actuator — Make sure it isn’t physically stuck or misaligned.
   
3. Listen for consistency — If the noise happens even when the vehicle is off and you manually rotate the driveshaft, that points to internal gear/bearing issues.
   
4. Professional inspection — Rattling metal inside a transfer case usually requires opening it up to inspect for broken gears or bearings. Driving with it could cause severe damage.
   

Bottom line:
While a stuck actuator could prevent 4WD engagement, it doesn’t usually make loud rattling noises like loose metal. Your description sounds more like internal damage in the transfer case rather than just the actuator.