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 PerformanceDTC 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
Connector End View Reference
Description and Operation
Brake Assist System Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the brake booster vacuum sensor.
- Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 2 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
- Verify the scan tool ECM Brake Booster Pressure Sensor parameter is less than 0.15 volt.
- 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.
- If all circuits test normal, test or replace the brake booster pressure sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
| ⇒ | If greater than the specified range, test the signal circuit terminal for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
