GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Sonoma Pickup - 2WD 🢒 Engine 🢒 Engine Electrical 🢒 Transmission Jumps Out of Gear

Diagnostic Aids

The manual transmission can have a number of problems to make it jump out of gear. You should also perform a static shift and a dynamic shift test. Some of the most common ones are misalignment of the transmission to engine, the clutch housing loose, or misalignment. The transmission should also be checked for worn or damaged input bushing to flywheel or worn or damaged input and output shaft bearings. An bent input shaft could also be the result of the transmission jumping out of gear. When going into the internal part of the transmission also check for worn detent springs, synchronizers, worn teeth on the gears or even worn thrust washers. When doing inspections of the manual transmission you should inspect all internal parts for worn or damaged parts.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step is inspecting for the position of the shift control closeout boot.

    2.

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

    3.

  3. This step is checking for worn or damaged internal parts.

Step

Action

Yes

No

DEFINITION: Gear disengagement occurs during normal operation.

1

Did you review the manual transmission symptom 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 4

3

Reposition or replace the shift tower. Refer to Shift Lever 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 Shift Lever 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 Engine Mount Replacement - Left Side , Engine Mount Replacement - Right Side in Engine Mechanical - 5.7 L or Transmission Replacement .

Did you find and repair the condition?

System OK

Go to Step 8

8

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

Are there 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.

Are there 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 in Clutch.

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:
    • Gearshift
    • Transmission gears
    • Bearings

Is there any worn or damaged components?

Go to Step 13

System OK

13
  1. Replace any worn or damaged components. Refer to Transmission/Transaxle Unit Repair Manual.
  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