Buick Regal: DTC P0571

Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

DTC Descriptor

DTC P0571

Cruise Control Brake Switch Circuit

Circuit/System Description

• For an overview of the component/system, refer to:Cruise Control Description and Operation (Without Adaptive Cruise Control) or Cruise Control Description and Operation (With Adaptive Cruise Control)
• The K20 sends a serial data message to the K9 indicating the B22 function that has been requested.

Conditions for Running the DTC

• Ignition/Vehicle=On
• Vehicle Speed.=Greater than 40 km/h (25 MPH)
• Cruise Control=On

Frequency the DTC runs=Continuously - After the running conditions are met - For greater than 5 s.

Conditions for Setting the DTC

Cruise Control Switch Signal=Invalid Serial Data

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category=Type C DTC

Conditions for Clearing the DTC

DTCs listed in the DTC Descriptor Category=Type C DTC

Reference Information

Schematic Reference

Cruise Control Wiring Schematics

Connector End View Reference

Component Connector End View Index

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

Circuit/System Verification

1. Ignition - On / Vehicle - In Service Mode.

2. Verify there are no other DTCs set, except for DTC P0571.

• If any other DTCs are set

Refer to:Diagnostic Trouble Code (DTC) List - Vehicle

• Go to next step: If no other DTCs are set

3. Replace the component:K20 Engine Control Module.

4. Operate the vehicle within the Conditions for Running the DTC. - Verify the DTC does not set.

• If DTC P0571 is set

Replace the component:K9 Body Control Module

• Go to next step: If the DTC is not set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification.

For control module replacement, programming, and setup refer to: Control Module References.

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