P0572

DTC P0572 or P0573

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 not longer exists.
* A history DTC will clear after 40 malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

* Exterior Lights Schematics (Exterior Lights Schematics)
* Cruise Control Schematics ([1][2]Cruise Control)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Cruise Control Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

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 X2 and TCM F module (LNF)
* ECM X1 and TCM F module (LE5)

2. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.

* ECM terminal 52 (LNF)
* ECM terminal 7 (LE5)

3. Ignition ON, press and release the brake pedal. 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 ECM module.
5. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.

* TCM terminal 38 F (LNF)
* TCM terminal 38 F (LE5)

6. Ignition ON, press and release the brake pedal. 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 an open/high resistance. If the circuit test normal, replace the ECM module.

7. If all circuits test normal, replace the TCM.

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