GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2008 🢒 Sierra - 4WD 🢒 Transmission/Transaxle 🢒 Manual Transmission - Tremec 5-Speed (TZ0) 🢒 Transmission Jumps Out of Gear

Diagnostic Aids

You should perform a static shift test and a dynamic shift test. The manual transmission can have many conditions that make it jump out of gear. Some of the most common conditions are misalignment of the transmission to engine, a loose clutch housing, or misalignment. The transmission should also be inspected for worn or damaged input bushing to flywheel or worn or damaged input and output shaft bearings. A bent input shaft could also be the result of the transmission jumping out of gear. While inspecting the internal part of the transmission, also inspect for worn detent springs, synchronizers, worn teeth on the gears, or worn thrust washers.

Inspect all internal components for being worn or damaged.

Test Description

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

  1. This step inspects for the shift control closeout boot position.

    2.

  2. This step inspects for worn or damaged transmission or engine mounts.

    3.

  3. This step inspects for worn or damaged internal components.

Step

Action

Yes

No

DEFINITION: Gear disengagement occurs during normal operation.

1

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

Go to Step 2

Go to Symptoms - Manual Transmission

2

Inspect the transmission shift tower.

Is the boot out of position?

Go to Step 3

Go to Step 3

3

Reposition or replace the shift tower. Refer to Shift Tower Replacement.

Did you find and repair the condition?

System OK

Go to Step 4

4

Inspect the transmission shift control.

Is the shift lever loose or damaged?

Go to Step 5

Go to Step 6

5

Replace the transmission shift lever. Refer to Transmission Control Lever Knob Replacement and Transmission Control Lever Boot Replacement.

Did you find and repair the condition?

System OK

Go to Step 6

6

Inspect the engine and/or transmission mounts.

Are the engine and/or transmission mounts worn or damaged?

Go to Step 7

Go to Step 8

7

Replace the engine mounts and/or transmission mounts. Refer to the appropriate procedure:

Did you find and repair the condition?

System OK

Go to Step 8

8

Inspect the engine and/or transmission mounts for loose fasteners.

Did you find any loose fasteners?

Go to Step 9

Go to Step 10

9

Tighten the engine mount and/or transmission mount fasteners to specifications. Refer to Fastener Tightening Specifications.

Did you find and repair the condition?

System OK

Go to Step 10

10

Inspect the clutch housing for loose bolts or misalignment.

Did you find any loose bolts or misalignment?

Go to Step 11

Go to Step 12

11

Tighten any loose housing bolts and/or align the housing. Refer to Fastener Tightening Specifications.

Did you find and repair the condition?

System OK

Go to Step 12

12

  1. Remove the transmission. Refer to Transmission Replacement.
  2. Disassemble and inspect the following internal components for wear or damage:
    3. • Gearshift
    • Transmission gears
    • Bearings

Did you find any worn or damaged components?

Go to Step 13

System OK

13
  1. Replace worn or damaged components, as necessary.
  2. Install the transmission. Refer to Transmission Replacement.

Did you find and repair the condition?

Go to Step 14

Go to Diagnostic Aids

14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1