Four wheel drive system not working properly

1999 GMC SUBURBAN
206,311 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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A.BENNETT
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  • 2 POSTS
Has new transfer case motor and new electric switch.
Will automatically switch from 4hi to 4lo or auto4wheel.
You think it's in 2hi or 4hi then when you start driving it will automatically do whatever it wants. Sometimes it locks in 4lo and has to be put in neutral or a gear to be taken out. The 4lo light will also flash when it's in 2hi or 4 hi.
Mar 12, 2022 at 3:14 PM
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ASEMASTER6371
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  • 52,796 POSTS
Good morning,

The first thing I would do is check the oil level in the case. It must be full for it to work correctly.

What kind of oil did you use when you changed it out? That is critical.


NVG 246-NP8 .................... Automatic Transfer Case Fluid GM Part No. 12378508

Roy
Mar 13, 2022 at 1:54 AM
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A.BENNETT
  • MEMBER
  • 2 POSTS
Was not changed out yet, topped off with transmission fluid.
Mar 13, 2022 at 3:34 PM
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ASEMASTER6371
  • CERTIFIED EXPERT
  • 52,796 POSTS
Change it and use the exact fluid I posted. It is critical to use the correct fluid.

Roy
Mar 14, 2022 at 4:34 AM