GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Transmission/Transaxle 🢒 Manual Transaxle - MU3 🢒 Transmission Does Not Shift into One Gear

Diagnostic Aids

If the transaxle shifts into gear and then jumps out of gear, refer to Transmission Jumps Out of Gear . If it is an intermittent condition, other driveline components may be faulty.

Test Description

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

  1. This step is to confirm that the clutch is not slipping. During certain conditions, the clutch may slip, and feel as though the transaxle is not in gear.

    2.

  2. A static shift test is performed by shifting into all gears with the engine not operating. While performing the test, you should note how the shift lever movement feels. Also, feel for the shift rails moving freely, the detent plungers operating when coming out of a gear and going in the next gear, and the synchronizer sleeve movement.

    3.

  3. A dynamic shift test is performed by shifting into all gears with the engine operating. Test for the correct mesh of the synchronizers sleeve and the speed gear selector teeth. Move the shift lever and feel for the synchronizer sleeve to just release from the gear, then let up on the clutch pedal. Depress the clutch pedal and move the shift lever to engage that gear again, to ensure full travel of the shift components.

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 transaxle.

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 in Clutch.

Is the clutch working properly?

Go to Step 3

Go to Clutch Pressure and Driven Plate Replacement in Clutch

3

  1. Perform a static shift test on the transaxle.
  2. Test for the following conditions:
    3. • 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
    • Shift cable binding
    • Shift cable proper adjustment

Were you able to shift into the gear position that has the concern?

Go to Step 6

Go to Step 4

4

Remove the floor console. Refer to Front Floor Console Replacement in Instrument Panel, Gages, and Console.

Inspect for the following conditions:

    • Loose mounting
    • Foreign debris

Did you find and repair the condition?

Go to Step 9

Go to Step 6

5

Inspect for proper shift cable adjustment. Refer to Shift Cable Adjustment .

Did you find and repair the condition?

Go to Step 9

Go to Step 6

6

  1. Perform a dynamic shift test on the transaxle.
  2. Test for the following conditions:
    3. • 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 8

Go to Step 7

7
  1. Remove the transaxle. Refer to Transmission Replacement .
  2. Disassemble the transaxle. Refer to Transmission Disassemble in Manual Transmission MU3 - Unit Repair.
  3. Inspect the following transaxle internal components for wear or damage:
    4. • The shift forks
    • The internal shift control lever

Did you find and repair the condition?

Go to Step 9

Go to Step 8

8
  1. Remove the transaxle. Refer to Transmission Replacement .
  2. Disassemble the transaxle. Refer to Transmission Disassemble in Manual Transmission MU3 - Unit Repair.
  3. Inspect the following transaxle internal components for wear or damage:
    4. • 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 9

Go to Diagnostic Aids

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1