Buick Regal: DTC P0556, P0557, or P0558
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.
- Refer to Diagnostic Procedure Instructions for 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 brake booster vacuum sensor monitors the pressure in the brake booster.
The engine control module
supplies a 5 V reference and a low reference circuit to the brake booster vacuum
sensor. The vacuum
sensor supplies a voltage signal in relation to the pressure in the brake
booster to the engine control
module.
Conditions for Running the DTC
P0556
Engine Running.
P0557 or P0558
Ignition ON/Ignition ON/Vehicle in Service Mode.
Conditions for Setting the DTC
P0556
The engine control module detects brake booster vacuum as being less than the
intake manifold vacuum for
more than 100 ms.
P0557
The engine control module detects less than 0.01 V on the brake booster
sensor signal circuit for more than
12.5 ms.
P0558
The engine control module detects greater than 4.9 V on the brake booster
sensor signal circuit for more
than 12.5 ms.
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 Wiring Schematics
Connector End View Reference
Component Connector End View Index
Description and Operation
Brake Booster Vacuum Assist Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
DTC Type Reference
Refer to Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Refer to Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF/Ignition OFF/Vehicle OFF and all vehicle systems OFF,
disconnect the harness
connector at the B19B Brake Booster Vacuum Sensor. It may take up to 2 min for
all vehicle systems
to power down.
2. Test for less than 10 Ω between the low reference circuit terminal 2 and
ground.
- Disconnect the harness connector at the K20 Engine Control Module.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If less than 10 Ω
3. Ignition ON/Ignition ON/Vehicle in Service Mode.
4. Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 3 and ground.
- Ignition OFF/Ignition OFF/Vehicle OFF, disconnect the harness connector
at the K20 Engine
Control Module.
- Test for infinite resistance between the 5 V reference circuit and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the 5 V reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Ignition OFF/Ignition OFF/Vehicle OFF, disconnect the harness connector
at the K20 Engine
Control Module, ignition ON.
- Test for less than 1 V between the 5 V reference circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If between 4.8 - 5.2 V
5. Test for less than 1 V between the B19B Brake Booster Vacuum Sensor signal
circuit terminal 1 and
ground.
- Ignition OFF/Ignition OFF/Vehicle OFF, disconnect the harness connector
at the K20 Engine
Control Module, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K20 Engine Control Module.
- Go to next step: If less than 1 V
6. Ignition OFF/Ignition OFF/Vehicle OFF, disconnect the harness connector at
the K20 Engine Control
Module.
7. Test for infinite resistance between the B19B Brake Booster Vacuum Sensor
signal circuit terminal 1
and ground.
- If less than infinite resistance
Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
8. Test for less than 2 Ω in the B19B Brake Booster Vacuum Sensor signal
circuit end to end.
Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
9. Replace the B19B Brake Booster Vacuum Sensor.
10. Verify the DTC does not set while operating the vehicle under Conditions
for Running the DTC.
Replace the K20 Engine Control Module.
- Go to next step: If the DTC does not set
11. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Refer to Control Module References for Engine Control Module replacement,
programming and setup.
READ NEXT:
NOTE: The following steps must be completed before using the symptom
tables.
1. Perform the Brake System Vehicle Road Test before using the hydraulic
brake symptom tables in
order to duplicate the c
WARNING: Brake fluid may irritate eyes and skin. In case of contact,
take the following
actions:
Eye contact - rinse thoroughly with water.
Skin contact - wash with soap and water.
If ingested -
Preliminary Inspections
1. Visually inspect easily accessible brake system components for obvious
damage and/or leaks which
may indicate that the vehicle should not be driven until further inspection
SEE MORE:
Instrument Panel Illumination
Control
The brightness of the instrument
cluster display, infotainment display
and controls, steering wheel
controls, and all other illuminated
controls, as well as feature status
indicators can be adjusted.
The knob for this feature is on the
instrument panel beside
For the proper type of replacement
bulbs, or any bulb changing
procedure not listed in this section,
contact your dealer.
Halogen Bulbs
Warning:
Halogen bulbs have pressurized
gas inside and can burst if you
drop or scratch the bulb. You or
others could be injured. Be sure
to read and follow the i