Generator Noise Diagnosis

Generator Noise Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

Diagnostic Aids

Noise from a generator may be due to electrical or mechanical noise. Electrical noise or magnetic whine usually varies with the electrical load placed on the generator and is a normal operating characteristic of all generators. When diagnosing a noisy generator, it is important to remember that loose or misaligned components around the generator may transmit the noise into the passenger compartment and that replacing the generator may not solve the problem.

Circuit/System Testing

1. Start the engine. Verify the noise can be heard. Compare the concern to a similar vehicle.
2. Perform a charging system test. Verify that the generator is charging properly. Refer to Charging System Test (Testing and Inspection).

• If the battery is discharged, charge the battery. Go to Battery Charging (Procedures)

• If the generator fails the charging system test, replace the generator.

3. Verify that the power steering fluid level is not low. Refer to Checking and Adding Power Steering Fluid (Checking and Adding Power Steering Fluid).

• If the power steering fluid level is low, go to Power Steering Fluid Leaks (Power Steering Fluid Leaks).

4. Inspect the generator, generator mounting, wiring harness, heater hoses, A/C lines, or other accessory equipment that may be misrouted or be the cause of noise being transmitted into the passenger compartment.
5. Ignition OFF, remove the engine drive belt. Refer to one of the following:

* Drive Belt Replacement ()for the 4.2 L engine (LL8)
* Drive Belt Replacement - Accessory (Drive Belt Replacement - Accessory)for the 5.3 L engine (LH6)

6. Verify the generator, A./C compressor, water pump pulley, power steering pump, idler pulley(s), and tensioner pulley(s) spin freely, and that the pully bearings are not loose.

• If any of the pulleys do not spin freely, or has a loose bearing, replace the affected component.

7. Start the engine with the drive belt removed. Verify that the noise goes away. Operate the engine for no longer than 30 seconds.

• If the noise is still present, the generator is not the cause of the noise.

8. Loosen all generator mounting bolts and ensure the generator is properly aligned. Tighten the mounting bolts to specification. Refer to Generator Replacement (With 4.2L Engine) ()Generator Replacement (5.3L Engine) ().
9. If the noise is still present, replace the generator.

Repair Instructions

* Drive Belt Tensioner Replacement ()for the 4.2 L engine (LL8)
* Drive Belt Tensioner Replacement - Accessory (Drive Belt Tensioner Replacement - Accessory)for the 5.3 L engine (LH6)
* Drive Belt Idler Pulley Replacement (Service and Repair)for the 4.2 L engine (LL8)
* Drive Belt Idler Pulley Replacement (Service and Repair)for the 5.3 L engine (LH6)
* Generator Replacement (With 4.2L Engine) ()Generator Replacement (5.3L Engine) ()