GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C0299:  Brake Booster Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Brake Booster Vacuum Sensor

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C0299

Circuit/System Description

The EBCM monitors the vacuum level in the power brake booster, and will set a DTC if the vacuum is too low.

Conditions for Running the DTC

    • The ignition is ON.
    • Ignition voltage is greater than 9 volts.
    • The engine is running for the vacuum related fault to set.

Conditions for Setting the DTC

    • A condition in which no vacuum is detected in the power brake booster for approximately 10 seconds after start-up.
    • A condition in which low vacuum is detected in the power brake booster for approximately 60 seconds or longer after start-up, or is detected while driving.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Antilock Brake System Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

  1. Verify that a vacuum leak is not present, refer to Brake Assist System Diagnosis .
  2. Verify that the following DTC is not set: C1100.
  3. If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .