P0573

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 Descriptor
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), powertrain control module (PCM), transmission control module (TCM) and throttle actuator control (TAC) module (as equipped). 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 ignition is ON.
* The engine is running.
* Battery voltage is greater than 11.5 volts.



Conditions for Setting the DTC

P0572

The ECM/PCM 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/PCM 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.


Action Taken When the DTC Sets

* The ECM/PCM stores the DTC to memory.
* The ECM/PCM will record the operating conditions at the time the diagnostic failed. The ECM/PCM stores this information in Failure Records.
* The cruise control system becomes inoperative.



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 Diagrams)
* Cruise Control Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) (Cruise Control Description and Operation (Conventional Cruise Control))Cruise Control Description and Operation (Adaptive Cruise Control) (Cruise Control Description and Operation (Adaptive Cruise Control))
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

Programming and Relearning (Programming and Relearning) for scan tool information


Circuit/System Testing

1. Ignition OFF, disconnect the harness connectors at the control modules for the appropriate engine RPO listed below.

* PCM X1 and TAC module (with L26)
* ECM X1 and TCM (with LD8 or L37)

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

* TAC terminal 6 (with L26)
* TCM terminal 42 (with LD8 or L37)

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 TAC module (with L26) or the TCM (with LD8 or L37).
5. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.

* PCM terminal 32 X1 (with L26)
* ECM terminal 77 X1 (with LD8 or L37)

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 appropriate TAC module (with L26) or the TCM (with LD8 or L37).

7. If all circuit tests normal, replace the appropriate PCM (with L26) or the ECM (with LD8 or L37).



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Programming and Relearning (Programming and Relearning) for ECM, PCM, TAC or TCM module replacement, setup, and programming