GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

DEFINITION: While shifting from HI range to LO range, there is gear clashing or no HI range.

Review the Symptoms - Transfer Case and perform the necessary inspections.

Mode shift clash

  1. Disassemble the transfer case. Refer to Transfer Case Disassemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  2. Inspect the synchronizer for being faulty. Refer to Transfer Case Cleaning and Inspection in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  3. Replace the synchronizer if it is faulty. Refer to Transfer Case Assemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.

Mode block

  1. Disassemble the transfer case. Refer to Transfer Case Disassemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  2. Inspect the range sleeve for sliding freely on the mainshaft. Refer to Transfer Case Cleaning and Inspection in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  3. Inspect the synchronizer for being faulty. Refer to Transfer Case Cleaning and Inspection in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  4. Replace the range sleeve and mainshaft if they are faulty. Refer to Transfer Case Assemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.
  5. Replace the synchronizer if it is faulty. Refer to Transfer Case Assemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.

If the symptoms occur during cold temperatures, flush and fill the front axle with synthetic fluid. Refer to Lubricant Change in Front Differential.

Worn or melted range fork pads

Replace the range fork assembly if the pads are faulty. Refer to Transfer Case Assemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.

Damaged range fork

Replace the range fork assembly if it is damaged. Refer to Transfer Case Assemble in Transmission/Transaxle/Transfer Case Unit Repair Manual.