P0573

DTC P0573

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0573 00
- Brake Switch Circuit 1 High Voltage

Diagnostic Fault Information






Circuit/System Description

The torque converter clutch (TCC) signal circuit is a high voltage input to the body control module (BCM), engine control module (ECM) and transmission control module (TCM). The ECM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The BCM monitors the stop lamp switch to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a GMLAN serial data message to the ECM indicating that the brake pedal has been applied. The ECM senses a high voltage signal on the TCC signal circuit when 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

The ECM detects a high voltage on the TCC brake signal circuit when the serial data message from the BCM indicates the brakes are not applied.

Action Taken When the DTC Sets

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

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.

Diagnostic Aids

Ensure all the stop lamps operate properly. Refer to Exterior Lighting Systems Description and Operation to avoid misdiagnosis. If the vehicle stop lamps operate improperly, refer to Symptoms - Lighting Systems.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the brake switch.
2. Ignition ON, verify that a test lamp does not illuminate between the stop lamp stop lamp switch harness terminal A and ground.

• If the test lamp illuminates, test the TCC brake signal circuit for a short to voltage.

3. If the circuit tests normal, test or replace the stop lamp switch. If the component and all circuit tests are normal, replace the ECM.

Component Testing

Switch Test

1. Ignition OFF, disconnect the stop lamp switch.
2. With the brake pedal released, measure for infinite resistance between terminals A and B of the switch.

• If resistance is measured, replace the switch.

3. With the brake pedal released, measure for less than 1.0 ohm resistance between terminals C and D of the switch.

• If resistance is not as specified, replace the switch.

4. With the brake pedal applied, measure for less than 1.0 ohm resistance between terminals A and B of the switch.

• If resistance is not as specified, replace the switch.

5. With the brake pedal applied, measure for infinite resistance between terminals C and D of the switch.

• If resistance is measured, replace the switch.

Repair Instructions

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

* Stop Lamp Switch Replacement (Non-Adjustable Pedal) Stop Lamp Switch Replacement (Adjustable Pedal)