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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 20 (Manual Transmission - NV 3500 - Service) >> Diagnostic Information and Procedures >> Transmission Does Not Shift into One Gear >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to step numbers on diagnostic table.

  1. 2:  This step is to confirm that clutch is not slipping. During certain conditions, clutch may slip, and feel as though transmission is not in gear.
  2. 3:  A static shift test is performed by shifting into all gears with engine not operating. While performing test, you should note how shift lever movement feels. Also, feel for shift rails moving freely, detent plungers operating when coming out of a gear and going in next gear, and synchronizer sleeve movement.
  3. 5:  A dynamic shift test is performed by shifting into all gears with engine operating. Test for correct mesh of synchronizers sleeve and speed gear selector teeth. Move shift lever and feel for synchronizer sleeve to just release from gear, then let up on clutch pedal. Depress clutch pedal and move shift lever to re-engage that gear, to ensure full travel of shift components.
Transmission Does Not Shift into One Gear

Step Action Yes No
DEFINITION: The shift lever will not move into a particular gear position, or when it is in a gear position, power is not delivered through the transmission.
1 Did you review the Symptoms - Manual Transmission, and perform the necessary inspections? Go to Step 2  Go to Symptoms - Manual Transmission 
2 Inspect the clutch system for slipping. Refer to Clutch Slipping .
Is the clutch working properly?		 Go to Step 3  Go to Clutch Assembly Replacement
3
  1. Perform a static shift test on the transmission.
  2. Test for the following:
    • Blockage preventing full shift lever movement
    • Excessive movement in the shift lever
    • Binding in the shift lever
    • Detent plungers or shift rails binding
    • Synchronizer sleeve moving on the hub and pressure pieces
Were you able to shift into the gear position that has the concern?		 Go to Step 5  Go to Step 4 
4 Remove the shift tower and inspect for worn or faulty components. Refer to Shift Lever Assembly Replacement .
Did you find and repair the condition?		 Go to Step 8  Go to Step 5 
5
  1. Perform a dynamic shift test on the transmission.
  2. Test for the following:
    • Detent plungers or shift rails binding
    • Synchronizer sleeve binding
    • Synchronizer sleeve engaging on the speed gear selector teeth
Were you able to shift into the gear position that has the concern?		 Go to Step 7  Go to Step 6 
6
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to TRANSMISSION DISASSEMBLE .
  3. Inspect the following transmission internal components for wear or damage:
    • The shift forks
    • The internal shift control lever
Did you find and repair the condition?		 Go to Step 8  Go to Step 7 
7
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to TRANSMISSION DISASSEMBLE .
  3. Inspect the following transmission internal components for wear or damage:
    • The synchronizer sleeve selector teeth
    • The speed gear selector teeth
    • The speed gear axial clearance for being excessive
    • The speed gear to mainshaft bearings and journals
    • The countershaft for being broken
    • The mainshaft for being broken
    • The countershaft gear for being stripped
    • The mainshaft gear for being stripped
Did you find and repair the condition?		 Go to Step 8  Go to Diagnostic Aids 
8 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 1 
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