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 Descriptors

DTC P0556: Brake Booster Pressure Sensor Performance

DTC P0557: Brake Booster Pressure Sensor Circuit Low Voltage

DTC P0558: Brake Booster Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

5-Volt Reference

P0557

P0557

P0557

P0558

P0556

Brake Booster Vacuum Sensor Signal

P0557

P0557

P0557

P0558

P0556

Low Reference

--

P0557

P0558

--

P0556

Circuit/System Description

The power brake booster vacuum sensor monitors the vacuum pressure in the brake booster. The ECM compares the readings of the engine vacuum with the brake booster vacuum.

Conditions for Running the DTC

P0556

    • Engine is running and vehicle speed is above 40 km/h (25 mph).
    • No TPS sensor DTCs are present.
    • The transmission is in drive.

P0557 or P0558

Engine running.

Conditions for Setting the DTC

P0556

    • Engine is running.
    • The ECM detects the vacuum level between the engine and brake booster is greater than 6kPa.

P0557

The ECM detects a short to ground or open in either the sensor signal circuit or the brake booster vacuum sensor.

P0558

The ECM detects an open with the sensor ground or a short to voltage in either the signal circuit or the brake booster vacuum sensor.

Action Taken When the DTC Sets

    • DTCs P0556, P0557 or P0558 are Type B DTCs.
    • ABS warning indicator is illuminated.

Conditions for Clearing the DTC

DTCs P0556, P0557 or P0558 are Type B DTCs.

Reference Information

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Brake Assist System Description and Operation

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the brake booster vacuum sensor.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 2 and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
  5. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  6. Verify the scan tool ECM Brake Booster Pressure Sensor parameter is less than 0.15 volt.
  7. If greater than the specified range, test the signal circuit terminal for a short to voltage. If the circuit tests normal, replace the ECM.
  8. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 1. Verify the scan tool ECM Brake Booster Pressure Sensor parameter is greater than 4.75 volts.
  9. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  10. If all circuits test normal, test or replace the brake booster pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Brake Booster Vacuum Sensor Replacement
    •  Control Module References for ECM replacement, setup, and programming