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 improperly routed or be the cause of noise being transmitted into the passenger compartment.

4. Ignition OFF, remove the engine drive belt.

5. 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.

• If all belt driven components spin freely

6. Start the engine. Operate the engine for no longer than 30-40 seconds.

7. Verify that the noise goes away.

• If the noise is still present
The generator is not the cause of the noise. Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical for 2.0L engine or Symptoms - Engine Mechanical Symptoms - Engine Mechanical for 2.2L or 2.4L engine.

• If noise is no longer present

8. Inspect for worn accessory drive components or abnormalities such as severe cracking, bumps, or missing areas in the accessory drive belt and/or misalignment of system components

Repair Instructions

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