GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2002 🢒 Isuzu T-Series (Truck Line C) 🢒 Transmission/Transaxle 🢒 Manual Transmission - Isuzu MLD6Q 🢒 Transmission Shifts Hard

Diagnostic Aids

An intermittent hard shift may be caused by an intermittent clutch condition.

Test Description

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

  1. A static shift test is performed by shifting into all of the gear positions with the engine not operating. While performing the test, you should note how the shift lever and the shift cable movement is felt. Also, while shifting from one gear to another, feel for binding in the shift rails. You should be able to feel the detent plungers operating when coming out of a gear and going into a gear.

    2.

  2. A dynamic shift test is performed by shifting into the gear positions with the engine operating. Test for the correct mesh of the synchronizers and for the clutch releasing correctly. When shifting into a gear and out of the gear, feel the shift detent plungers and for the synchronizers sleeve for moving freely.

Step

Action

Yes

No

DEFINITION: The transmission does not shift smoothly or without difficulty from one gear to the other.

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 clutch system for proper operation. Refer to Clutch System Description and Operation in Clutch.

Did you find and repair the condition?

Go to Step 11

Go to Step 3

3

  1. Perform a static shift test on the transmission.
  2. Test for the following:
    3. • Blockage preventing full shift lever movement
    • Excessive movement in the shift control and linkage
    • Binding in the shift lever
    • Detent plungers or shift rails binding
    • Shift cable binding

Did the transmission shift hard into all gears?

Go to Step 4

Go to Step 8

4

Disconnect the shift cable from the transmission.

Does the shift lever move easily?

Go to Step 9

Go to Step 5

5

Disconnect the shift cable from the shift lever.

Does the shift lever move easily?

Go to Step 6

Go to Step 7

6

Replace the shift cable. Refer to Shift Cable Replacement .

Did you find and repair the condition?

Go to Step 15

--

7

Replace the shift lever.

Did you find and repair the condition?

Go to Step 15

--

8

  1. Perform a dynamic shift test on the transmission.
  2. Test for the following:
    3. • Detent plungers or shift rails binding
    • Synchronizer sleeve binding
    • Gear clash into only one gear
    • Gear clash into all gears

Did the transmission shift hard into all gears?

Go to Step 9

Go to Step 11

9

Inspect the transmission for the correct fluid level and type of the transmission fluid. Refer to Lubrication Specifications .

Is the transmission at the correct level and proper fluid being used?

Go to Step 11

Go to Step 10

10

Drain and refill the transmission with the correct type fluid. Refer to Transmission Oil Changing .

Did you find and repair the condition?

Go to Step 15

Go to Step 11

11

Remove the shift control and inspect for worn or faulty components. Refer to Transmission Control Disassemble , Transmission Control Cleaning and Inspection , and Transmission Control Assemble .

Did you find and repair the condition?

Go to Step 15

Go to Step 12

12

Remove the transmission. Refer to Transmission Replacement .

Inspect the clutch pressure plate and/or clutch driven plate.

Is the clutch pressure plate and/or clutch driven plate worn or faulty?

Go to Step 13

Go to Step 14

13

Replace the clutch assembly. Refer to Clutch Assembly Replacement in Clutch.

Did you find and repair the condition?

Go to Step 15

Go to Step 14

14
  1. Disassemble the transmission. Refer to Transmission Disassemble .
  2. Inspect the transmission for faulty components in the gear that is hard to shift or clashing.
    3. • Excessive synchronizers blocking ring to gear clearance
    • Synchronizer hub external splines worn or damaged
    • Excessive axial clearance in the speed gear
    • Mainshaft to speed gear bearing or journal worn
    • Shift rail and the internal shift control lever components for wear or damage
  3. Replace worn or damaged components as necessary.

Did you find and repair the condition?

Go to Step 15

Go to Diagnostic Aids

15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1