P0557

DTC P0556, P0557, or P0558

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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/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

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.

Conditions for Clearing the DTC

DTCs P0556, P0557 or P0558 are Type B DTCs.

Reference Information
Schematic Reference

Hydraulic Brake Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Brake Assist System Description and Operation (Brake Assist System)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the brake booster vacuum sensor.
2. Ignition OFF, test for less than 5 ohm between the low reference circuit terminal 2 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.

• If less than the specified range, test the 5 V 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 V reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and the signal circuit terminal 1.

• If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Ignition OFF, disconnect the X1 harness connector at the ECM.
6. Test for infinite resistance between the signal circuit terminal 46 and ground.

• If not the specified value, test the signal circuit for a short to ground.

7. If all circuits test normal, test or replace the power brake booster vacuum sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Power Brake Booster Vacuum Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming