Transfer Case Will Not Shift

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

Cause	Correction
DEFINITION: While shifting from HI range to LO range, there is gear clashing, no HI range, or the transfer case will not shift from 4HI to 4HI Lock. Review the Symptoms - Transfer Case and perform the necessary inspections.
Shift detent lever	Inspect for the following conditions: The shift detent lever at the shift fork cams for being worn The shift detent lever torsion spring for being faulty Refer to Cleaning and Inspection . Replace the following components if found faulty: The shift detent lever cam The shift detent lever spring Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low range shift fork	Inspect the high low shift fork for the following conditions: Worn shift fork pads The roller on the shift fork for wear or damage Cracked or bent shift fork Refer to Cleaning and Inspection . Replace the following components if found faulty: The shift fork pads The shift fork Refer to Transfer Case Disassemble and Transfer Case Assemble .
Range sleeve	Inspect the range sleeve for the following conditions: Engagement teeth for burrs or damage Sliding freely on the mainshaft The range sleeve shift fork collar for excessive wear Refer to Cleaning and Inspection . Replace the range sleeve if it is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low planetary carrier	Inspect the high/low planetary engagement teeth for burrs or damage. Refer to Cleaning and Inspection . Replace the high/low planetary carrier if it is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Mainshaft front support bearing	Inspect for the following conditions: Failed front mainshaft support bearing in the input gear Journal on the mainshaft for excessive wear or damage Refer to Cleaning and Inspection . Replace the bearing if it is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble . Replace the mainshaft if it is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Lockup shift assembly	Inspect the lockup shift assembly for the following conditions: Shift assembly hub for binding Shift assembly sleeve for damage Burred or damaged engagement teeth Refer to Cleaning and Inspection . Replace the shift assembly if it is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Drive sprocket	Inspect for the following conditions: Engagement teeth on the drive sprocket for burrs or damage Worn bushing in the drive sprocket Journal on the mainshaft for excessive wear or damage Refer to Cleaning and Inspection . Replace the drive gear if it is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble . Replace the mainshaft if it is damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble .