GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Transmission/Transaxle 🢒 Manual Transmission - ZF S6-650 🢒 Transmission Locked in One Gear

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step is to ensure the use of the proper transmission fluid. A special fluid is used to ensure proper synchronizer operation, and for sufficient lubrication. Improper fluid may cause the synchronizers to stick or cause overheating of the transmission components.

    2.

  2. A static shift test is performed by shifting into all gears with the engine not operating. By confirming that the transmission can be shifted into all positions, ensures that the shift lever is not excessively worn or damaged.

    3.

  3. A dynamic shift test is performed by shifting into all of the gear positions with the engine operating. Test to ensure that the internal shift components are properly functioning.

Step

Action

Yes

No

DEFINITION: The transmission cannot be shifted out of a gear or the vehicle will not move because the transmission is locked.

1

Did you review the Symptoms - Manual Transmission and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Manual Transmission

2

Inspect for the correct type of transmission fluid.

Is the correct type of transmission fluid being used?

Go to Step 6

Go to Step 5

3

Drain and fill the transmission with the correct type of fluid. Refer to Transmission Fluid Replacement .

Did you find and repair the condition?

Go to Step 9

Go to Step 6

4

  1. Perform a static shift test on the transmission.
  2. Test for the shift lever moving to all positions.

Were you able to shift into all positions?

Go to Step 6

Go to Step 5

5
  1. Remove the shift lever. Refer to Shift Lever Assembly Replacement .
  2. Inspect for worn or faulty components.

Did you find and repair the conditions?

Go to Step 9

Go to Step 6

6

  1. Perform a dynamic shift test on the transmission.
  2. Test for being able to shift in and out of the gear with the concern.

Were you able to shift the transmission correctly?

Go to Step 7

Go to Step 8

7
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Inspect the clutch system for the clutch not releasing properly. Refer to Clutch System Description and Operation in Clutch.

Did you find and repair the condition?

Go to Step 9

Go to Step 8

8

  1. Disassemble the transmission. Refer to Transmission Disassemble .
  2. Inspect the following transmission internal components for wear or damage:
    • The shift rail
    • The internal shift control lever
    • The synchronizer components for being broken or faulty
    • The speed gears for being seized to the mainshaft

Did you find and repair the conditions?

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1