Transfer Case Will Not Shift

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. 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 or no HI range; or the transfer case will not shift from 2 wheel drive to 4 wheel drive. Review the Symptoms - Transfer Case and perform the necessary inspections.
Mode shift clash	Disassemble the transfer case. Refer to Transfer Case Disassemble . Inspect the synchronizer for being faulty. Refer to Two/Four Wheel Drive Shift Components Cleaning and Inspection . Replace the synchronizer if faulty. Refer to Transfer Case Assemble .
Mode block	Disassemble the transfer case. Refer to Transfer Case Disassemble . Inspect the synchronizer sleeve for sliding freely on the synchronizer hub. Inspect the synchronizer sleeve or synchronizer hub for being faulty. Replace the synchronizer sleeve or synchronizer hub if faulty. Refer to Transfer Case Assemble . If the symptoms occur during cold temperatures, flush and fill the front axle with synthetic fluid. Refer to Front Axle Lubricant Level Inspection (9.25 Inch Axle) .
High/low shift fork spring assembly	Inspect the high/low shift fork spring assembly for the following conditions: Worn high/low shift fork pin Worn cam Broken spring Refer to High/Low Shift Components Cleaning and Inspection . Replace the following components if found faulty: The high/low shift fork spring assembly The high/low shift fork pin Refer to High/Low Shift Fork Replacement .
High/low shift fork	Inspect the high/low shift fork for the following conditions: Worn shift fork pads Cracked or bent shift fork Refer to High/Low Shift Components Cleaning and Inspection . Replace the following components if found faulty: The shift fork pads The shift fork Refer to High/Low Shift Fork Replacement .
High/low clutch	Inspect the high/low clutch for the following conditions: Engagement teeth for burrs or damage Sliding freely on the rear output shaft The high/low clutch collar for excessive wear Refer to High/Low Shift Components Cleaning and Inspection . Replace the high/low clutch if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
Input shaft pilot bearing assembly	Inspect for the following conditions: Failed input shaft pilot bearing in the input shaft Journal on the rear output shaft for excessive wear or damage Refer to Rear Output Shaft Cleaning and Inspection and Front Output Shaft and Input Shaft Cleaning and Inspection . Replace the bearing if faulty. Refer to Input Shaft Pilot Bearing Replacement (Heavy Duty and Super Heavy Duty) . Replace the rear output shaft if damaged. Refer to Transfer Case Disassemble and Transfer Case Assemble .
High/low planetary carrier assembly	Inspect the high/low planetary engagement teeth for burrs or damage. Refer to High/Low Planetary Carrier Cleaning and Inspection . Replace the high/low planetary carrier assembly if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .