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 | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
5-Volt Reference | P0557 | P0557 | P0558 | P0556 |
Brake Booster Vacuum Sensor Signal | P0557 | P0557 | P0558 | P0556 |
Low Reference | -- | P0557 | -- | P0556 |
Circuit/System Description
The brake booster pressure sensor measures the negative air pressure or vacuum reserve in the brake booster assembly. During engine running conditions, the brake booster pressure sensor signal circuit voltage varies, depending on the vacuum reserve internal to the brake booster.
Conditions for Running the DTC
P0556
Engine running at idle.
P0557 or P0558
Ignition ON.
Conditions for Setting the DTC
P0556
The ECM detects brake booster vacuum as being less than the intake manifold vacuum.
P0557
The ECM detects open/high resistance, or short to ground on the brake booster sensor signal circuit.
P0558
The ECM detects short to voltage on the brake booster sensor signal circuit.
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
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
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.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and the signal circuit terminal 3.
- Ignition OFF, disconnect the harness connector at the ECM.
- Ignition OFF, test for infinite resistance between the signal circuit terminal 29 and ground.
- If all circuits test normal, test or replace the power brake booster vacuum 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 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. |
| ⇒ | If not the specified value, test the signal circuit for a short to ground. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
