Alternator: Testing and Inspection

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.

3. 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.

4. Ignition OFF, remove the engine drive belt. Verify the generator, A/C compressor, water pump pulley, power steering pump, idler pulley, and tensioner pulley spin freely.

• If any of the pulleys do not spin freely, replace the affected component.

5. Start the engine, with the drive belt removed. Verify that the noise goes away. Operate the engine for no longer than 30-40 seconds.

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

6. Loosen all generator mounting bolts and ensure the generator is properly aligned. Tighten the mounting bolts to specification, refer to Generator Replacement (V8) Service and RepairGenerator Replacement (V6) Service and RepairGenerator Replacement (Diesel) Service and Repair.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Drive Belt Replacement for the 4.3L engine

* Drive Belt Replacement for the 6.6L Diesel engine

* Drive Belt Replacement - Accessory Drive Belt Replacement - Accessory for the 4.8L or 5.3L engines

* Air Conditioning Compressor Belt Replacement Air Conditioning Compressor Belt Replacement for the 4.8L or 5.3L engines

* Generator Replacement (V8) Service and RepairGenerator Replacement (V6) Service and RepairGenerator Replacement (Diesel) Service and Repair