Verify the complaint. Define the type of noise, and when the noise occurs.

Did you verify the complaint?

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Go to Step 2

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Does the noise occur during high brake pedal efforts, with quick pedal release?

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Go to Step 3

Go to Step 4

Compare the system to a known acceptable system.

Does the acceptable system make the same noise?

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System OK

Go to Step 1

Does the noise occur under any of the following conditions?

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Go to Step 5

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1. Obtain a vehicle with a known acceptable brake booster system.
2. Run both vehicles until the engines reach normal operating temperature.
3. In both vehicles, duplicate the operating condition associated with the noise. Listen for the noise.
4. Compare the results.

Does the acceptable system make the same noise?

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System OK

Go to Step 1