GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

The chirping noise may be intermittent due to moisture on the drive belts or the accessory drive pulleys. In order to duplicate the customer concern, it may be necessary to spray a small amount of water onto the drive belts. If spraying water onto the drive belts duplicates the symptom, cleaning the accessory drive pulleys may be the most probable solution.

A loose or improper installation of a body or suspension component, or other items on the vehicle may also cause the chirping noise.

Test Description

The numbers below refer to the steps in the diagnostic table.

  1. The chirping noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed any further in this table.

  2. The noise may be an internal engine noise. Remove the drive belts and operate the engine for a few seconds, this will verify if the chirping noise is related to the drive belts or not. With the drive belts removed the water pump will not operate and the engine may overheat. Also DTCs may set when the engine is operated with the drive belts removed.

  3. Inspect the drive belts for signs of pilling. Pilling is the small balls, pills, or strings in the drive belt grooves caused by the accumulation of rubber dust.

  4. Misalignment of the accessory drive pulleys may be caused from improper mounting or incorrect installation of an accessory drive component, or the pulley may be bent inward or outward from a previous repair. Test for a misaligned accessory drive pulley using a straight edge in the pulley grooves across two or three pulleys. If a misaligned pulley is found, refer to that accessory drive component for the proper removal and installation procedure for that pulley.

  5. Inspection of the fasteners can eliminate the possibility that a incorrect bolt, nut, spacer, or washer was installed.

  6. Inspection of the accessory drive pulleys should include inspecting for bends, dents, or other damage to the pulleys that would prevent the drive belts from seating properly in the pulley grooves or on the smooth surface of the pulley when the back side of the drive belt is used to drive the pulley.

  7. Replacing the drive belts when it is not damaged or there is not excessive pilling will only be a temporary repair.

Step

Action

Yes

No

Notice: Do not use belt dressing on the drive belt. Belt dressing causes the breakdown of the composition of the drive belt. Failure to follow this recommendation will damage the drive belt.

DEFINITION: The following items are indications of chirping:

    • A high pitched noise that is heard once per revolution of the drive belts or an accessory drive pulley
    • Chirping may occur on cold damp start-up conditions and will subside once the vehicle reaches normal operating temperature.

1

Did you review the Symptoms - Engine Mechanical diagnostic information, and perform the necessary inspections?

Go to Step  2

Go to Symptoms - Engine Mechanical

2

Verify that there is a chirping noise.

Does the engine make the chirping noise?

Go to Step 3

Go to Diagnostic Aids

3

  1. Remove the drive belts. Refer to Drive Belt Replacement - Accessory .
  2. Operate the engine for no longer than 30-40 seconds.

Does the chirping noise still exist?

Go to Engine Noise on Start-Up, but Only Lasting a Few Seconds

Go to Step 4

4

Inspect for severe drive belt pilling exceeding 1/3 of the drive belt groove depth.

Do the drive belt grooves have pilling?

Go to Step 5

Go to Step 6

5

Clean the accessory drive pulleys with a suitable wire brush.

Were the accessory drive pulleys cleaned?

Go to Step 15

--

6

Inspect for a misaligned accessory drive pulleys.

Is there a misaligned accessory drive pulleys?

Go to Step 7

Go to Step 8

7

Replace and/or repair the misaligned accessory drive pulleys.

Were the misaligned accessory drive pulleys replaced and/or repaired?

Go to Step 15

--

8

Inspect for a bent or cracked accessory drive brackets.

Did you find any bent or cracked accessory drive brackets?

Go to Step 9

Go to Step 10

9

Replace the bent and/or cracked accessory drive brackets.

Was the bent and/or cracked accessory drive brackets replaced?

Go to Step 15

--

10

Inspect for incorrect, loose and/or missing fasteners.

Were there any incorrect, loose, and/or missing fasteners found?

Go to Step 11

Go to Step 12

11

  1. Replace any incorrect and/or missing fasteners.
  2. Tighten any loose fasteners. Refer to Fastener Tightening Specifications .

Were the fasteners replaced and/or tightened?

Go to Step 15

--

12

Inspect for a bent accessory drive pulleys.

Was a bent accessory drive pulleys found?

Go to Step 13

Go to Step 14

13

Replace the bent accessory drive pulleys.

Was the bent accessory drive pulleys replaced?

Go to Step 15

--

14

Replace the drive belts. Refer to Drive Belt Replacement - Accessory .

Was the drive belts replaced?

Go to Step 15

--

15

  1. Clear any codes.
  2. Run the engine in order to verify the repair.

Does the chirping noise still exist?

--

System OK