P0572
DTC P0572 or P0573
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 P0572
- Brake Switch Circuit 1 Low Voltage
DTC P0573
- Brake Switch Circuit 1 High Voltage
Diagnostic Fault Information
Circuit/System Description
The stop lamp switch signal circuit is a direct hardwire input from the body control module (BCM) to the engine control module (ECM) and the transmission control module (TCM). The modules monitor the stop lamp switch signal circuit to detect when the brake pedal has been applied. The BCM monitors the brake apply sensor signal circuit to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a serial data message to the modules and also a voltage signal on the stop lamp switch signal circuit indicating that the brake pedal has been applied.
Conditions for Running the DTC
* The engine is running.
* Battery voltage is greater than 11.5 volts.
Conditions for Setting the DTC
P0572
The ECM detects a low voltage signal on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are applied.
P0573
The ECM detects a high voltage signal on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are not applied.
Actions Taken When the DTC Sets
* The malfunction indicator lamp (MIL) will not illuminate.
* The cruise control system is disabled.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 40 malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
* Exterior Lights Schematics (Exterior Lights Schematics)
* Cruise Control Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Cruise Control Description and Operation (Description and Operation)
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)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connectors at the appropriate control modules listed below.
* ECM X1
* TCM
2. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.
* ECM terminal 9 (LZE/LZ4/LZG)
* ECM terminal 7 (LS4)
* TCM terminal 42
3. Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the TCM.
5. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.
* ECM terminal 9 (LZE/LZ4/LZG)
* ECM terminal 7 (LS4)
6. Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TCM.
7. If all circuits test normal, replace the ECM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning) for BCM, ECM, or TCM replacement, setup, and programming