Noise from a generator may be due to electrical or mechanical noise. Mechanical noise may be caused by a loose drive pulley, loose mounting bolts, worn or dirty bearings, or a defective stator. Electrical noise (magnetic whine) usually varies with the ampere 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.

1

Test the generator for proper operation using an appropriate generator tester. Refer to Charging System Check .

Is the generator operating properly?

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Go to Step 2

Go to Step 13

1. Start the engine. Verify that the noise can be heard.
2. Disconnect the connector from the generator.
3. Listen for the noise.

Has the noise stopped?

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Go to Step 12

Go to Step 3

1. Turn OFF the engine.
2. Remove the drive belt. Refer to Drive Belt Replacement in Engine Mechanical.
3. Spin the generator pulley by hand.

Does the generator shaft spin smoothly and without any roughness or grinding noise?

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Go to Step 4

Go to Step 13

Inspect the generator for a loose pulley and/or pulley nut.

Is the generator pulley or pulley nut loose?

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Go to Step 5

Go to Step 7

1. Remove the generator pulley.
2. Inspect the pulley and the shaft for damage or signs of overheating (due to a slipping pulley).

Is the pulley or the shaft damaged?

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Go to Step 13

Go to Step 6

1. Install the pulley.
2. Tighten the generator pulley nut to specification.
3. Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical.
4. Start the engine.

Has the noise decreased or stopped?

118 N·m (86 lb ft)

System OK

Go to Step 7

1. Loosen all of the generator mounting bolts.
2. Tighten the generator mounting bolts to specifications and in the proper sequence (if necessary). Refer to Generator Replacement .
3. Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical.
4. Start the engine.

Has the noise decreased or stopped?

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System OK

Go to Step 8

Inspect the generator for the following conditions:

Are the electrical connections pulling on the generator or are any hoses, etc. resting on the generator?

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Go to Step 9

Go to Step 10

1. Reroute the electrical connections to relieve the tension.
2. Reroute the hoses, etc. away from the generator.
3. Start the engine.

Has the noise decreased or stopped?

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System OK

Go to Step 10

Check the drive belt for proper tension. Refer to Drive Belt Replacement in Engine Mechanical.

Is the drive belt loose?

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Go to Step 11

Go to Step 12

1. Adjust the drive belt tension. Refer to Drive Belt Replacement in Engine Mechanical.
2. Start the engine.

Has the noise decreased or stopped?

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System OK

Go to Step 12

Compare the vehicle with a known good vehicle.

Do both vehicles make the same noise?

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System OK

Go to Step 13

Important: If no definite generator problems were found, be sure that all other possible sources of objectionable noise are eliminated before replacing the generator. Replacing the generator may not change the noise level if the noise is a normal characteristic of the generator or the generator mounting.

Replace the generator. Refer to Generator Replacement .

Has the noise decreased or stopped?

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System OK

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