GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

Schematic Reference: Brake Warning System Schematics

1

Did you review the Brake Warning System Description and Operation and the Brake Assist System Description and Operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - Hydraulic Brakes

2

Perform the Brake Assist System Diagnosis .

Did you find and correct the condition?

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Go to Step 8

Go to Step 3

3

  1. Disconnect the supplemental brake assist (SBA) harness connector.
  2. Turn the ignition ON.
  3. Use a DMM to measure the voltage between the supplement a brake assist signal circuit and a good ground.

Does the voltage measure greater than the specified value?

11 V

Go to Step 5

Go to Step 4

4

  1. Remove the instrument panel cluster (IPC) from the instrument panel. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  2. Test the supplemental brake assist signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 6

5

With the SBA harness connector still disconnected, start the engine.

Is the reduced brake power message displayed?

--

Go to Step 6

Go to Step 7

6

Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

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Go to Step 8

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7

Replace the supplemental brake assist pump motor assembly. Refer to Power Brake Booster Auxiliary Pump Replacement .

Did you complete the replacement?

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Go to Step 8

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8

Start the engine.

Is the reduced brake power message displayed?

--

Go to Step 2

System OK