GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 TrailBlazer - 4WD 🢒 General Information 🢒 Vibration Diagnosis and Correction 🢒 Vibration Analysis - Driveline

Step

Action

Yes

No

1

Has the Vibration Analysis - Road Testing table been completed?

Go to Step 2

Go to Vibration Analysis - Road Testing

2

Did you duplicate a vibration concern that occurs only during heavy acceleration at launch?

Go to Step 3

Go to Step 4

3

Is the vehicle equipped with a solid drive axle and at least 1 U-joint in the propeller shaft system?

Go to Step 26

Go to Step 4

4

Did you record frequency data from the J 38792-A , Electronic Vibration Analyzer (EVA) 2, during the Vibration Analysis - Road Testing procedure?

Go to Step 5

Go to Step 10

5

Based on the Vibration Analysis - Road Testing table, is the concern first order, sixth order, or a slightly higher multiple of first order driveline related?

Go to Step 6

Go to Step 8

6

Is the vehicle equipped with a rear mounted transaxle assembly?

Go to Step 7

Go to Step 11

7

Inspect the drive axle for proper operation. Refer to the Drive Axle diagnosis information.

Did you find and correct a condition?

Go to Step 32

Go to Step 2

8

Based on the Vibration Analysis - Road Testing table, is the concern second order driveline related?

Go to Step 9

Go to Step 10

9

Does the vehicle driveline contain any U-joints?

Go to Step 26

Go to Vibration Diagnostic Aids

10

Based on the Vibration Analysis - Road Testing table, is the concern a noise that is not felt?

Go to Vibration Diagnostic Aids

Go to Vibration Analysis - Road Testing

11
  1. Inspect the following components for wear and/or damage:
    2. • Inspect the propeller shafts for dents, damage, missing weights, and/or undercoating.
    • Inspect the U-joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
    • Inspect the prop shaft constant velocity (CV) joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
    • Inspect the prop shaft coupler assembly, or assemblies, if equipped, for excessive wear, looseness, and/or damage.
    • Inspect the prop shaft support bearing, if equipped, for damaged rubber components, worn bearings, looseness, and/or a deformed or cracked bracket.
    • Inspect the drive axle mounts, if equipped, for excessive wear, looseness, and/or damage.
  2. Replace any of the components found to be worn or damaged.

Did you find and correct a condition?

Go to Step 32

Go to Step 12

12

Attempt to duplicate the vibration in the stall. Refer to Vibration in Service-Stall Test (Non-Torque Sensitive) .

Were you able to duplicate the vibration?

Go to Step 16

Go to Step 13

13

Perform the Vibration in Service-Stall Test (Torque Sensitive) .

Were you able to duplicate the vibration?

Go to Step 14

Go to Vibration Diagnostic Aids

14

Is the vehicle front wheel drive with an all wheel drive system?

Go to Step 15

Go to Vibration Diagnostic Aids

15
  1. Remove the propeller shaft.
  2. Perform the Vibration in Service-Stall Test (Torque Sensitive) .

Is the vibration still present?

Go to Diagnostic Starting Point - Transfer Case for the NVG 226-NP8 or Diagnostic Starting Point - Transfer Case for the NVG 120-NR9

Go to Diagnostic Starting Point - Front Drive Axle

16

Was the vibration most evident under the transmission or the transfer case, if equipped?

Go to Step 17

Go to Step 20

17
  1. If the driveline joint at the transmission or transfer case is a U-joint, measure the prop shaft runout at the end closest to the transmission or transfer case. Refer to Propeller Shaft Runout Measurement .
  2. If the driveline joint at the transmission or transfer case is a CV joint, measure the runout of the transmission or transfer case output flange. Refer to Transfer Case Output Flange Runout Measurement .
  3. If the driveline joint at the transmission or transfer case is a coupler assembly, inspect the coupler assembly for excessive wear, looseness, missing or broken fasteners, and/or damage. Measure the runout of the transmission or transfer case output flange. Refer to Transfer Case Output Flange Runout Measurement .
  4. Replace components as necessary.

Did you find and correct a condition?

Go to Step 19

Go to Step 18

18
  1. Inspect the powertrain mounts for the following:
    2. • Loose and/or missing fasteners
    • Improper alignment
    • Cracked, dry-rotted, and/or oil-soaked insulators
    • Twisted, broken, torn, and/or collapsed insulators
    • Bent, twisted, and/or deformed brackets
  2. Replace the powertrain mounts as necessary.

Did you find and correct a condition?

Go to Step 19

Go to Step 20

19

Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 20

Go to Step 32

20
  1. Inspect the prop shaft U-joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
  2. Inspect the prop shaft CV joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
  3. Inspect the prop shaft coupler assembly for excessive wear, looseness, broken or missing fasteners, and/or damage
  4. Inspect the prop shaft support bearing assembly, if equipped, for damaged rubber components, worn bearings, and/or a deformed or cracked bracket.
  5. If the driveline joint at the drive axle is a U-joint, measure the runout of the complete prop shaft, or shafts. Refer to Propeller Shaft Runout Measurement .
  6. If the driveline incorporates a torque tube attached to the drive axle and the joint at the torque tube is a CV joint, coupler assembly, or bolt-on U-joint yoke, measure the runout of the torque tube input flange. Refer to Torque Tube Input Flange Runout Measurement .
  7. Replace components as necessary.

Did you find and correct a condition?

Go to Step 21

Go to Step 22

21

Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 22

Go to Step 32

22
  1. Measure the runout of the drive axle pinion input flange or shaft:
    2. • If the driveline joint at the drive axle is a U-joint and if the U-joint yoke is Not a bolt-on type, refer to Pinion Flange Runout Measurement .
    • If the driveline joint at the drive axle is a U-joint and if the U-joint yoke IS a bolt-on type, refer to Differential Pinion Input Shaft Runout Measurement .
    • If the driveline incorporates a torque tube attached to the drive axle, refer to Differential Pinion Input Shaft Runout Measurement .
    • If the driveline joint at the drive axle is a coupler assembly or a CV joint, refer to Differential Pinion Input Shaft Runout Measurement .
  2. For a direct-mount drive axle, inspect the mounts and/or bushings for excessive wear, looseness, and/or damage.
  3. Replace excessively worn or damaged components as necessary.

Did you find and correct a condition?

Go to Step 23

Go to Step 24

23

Perform the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Is the vibration still present?

Go to Step 24

Go to Step 32

24

Re-index the prop shaft. Perform the following steps:

  1. Raise and support the vehicle.
  2. Mark the position of the prop shaft to both the transmission or transfer case output shaft flange, and the drive axle input flange.
  3. Remove the prop shaft.
  4. Rotate the prop shaft 180 degrees to both of the flanges.
  5. Reinstall the prop shaft.
  6. Attempt to duplicate the vibration in the stall. Refer to the Vibration in Service-Stall Test (Non-Torque Sensitive) .

Was the vibration reduced or eliminated?

Go to Step 32

Go to Step 25

25

Return the prop shaft to it's original position and balance the prop shaft. Refer to Driveline System Balance Adjustment .

Were you able to balance the driveline system?

Go to Step 32

Go to Vibration Diagnostic Aids

26

Inspect the following components for wear and/or damage:

    • Inspect the prop shafts for dents, damage, missing weights, and/or undercoating.
    • Inspect the U-joint, or joints for excessive wear, looseness, and/or damage.
    • Inspect the prop shaft support bearing, if equipped, for damaged rubber components, worn bearings, looseness, and/or a deformed or cracked bracket.
    • Replace components as necessary.

Did you find and correct a condition?

Go to Step 32

Go to Step 27

27

Is the drive axle a direct-mount?

Go to Step 29

Go to Step 28

28
  1. Measure the vehicle trim height.
  2. Adjust the vehicle trim height if necessary.

Refer to the vehicle trim height inspection procedures.

Did you find and correct a condition?

Go to Step 32

Go to Step 29

29
  1. Measure the prop shaft angles. Refer to Driveline Working Angles Measurement .
  2. If necessary, adjust the prop shaft angles. Refer to Driveline Working Angles Adjustment .

Did you find and correct a condition?

Go to Step 32

Go to Step 30

30

Does this prop shaft system have only 1 U-joint?

Go to Vibration Diagnostic Aids

Go to Step 31

31
  1. Inspect the prop shafts for proper phasing. Refer to Propeller Shaft Phasing Inspection .
  2. If necessary, correct the prop shaft phasing. Refer to Propeller Shaft Phasing Correction .

Did you find and correct a condition?

Go to Step 32

Go to Vibration Diagnostic Aids

32
  1. Install or connect any components that were removed or disconnected during diagnosis.
  2. Perform the Vibration Analysis - Road Testing table. Refer to Vibration Analysis - Road Testing .

Is the vibration still present?

Go to Step 5

System OK