Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0572 00: Brake Switch Circuit 1 Low VoltageDiagnostic Fault Information
Circuit | Short to Ground | Open or High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Stop Lamp Switch Signal | P0572 00 | P0572 00 | P0573 00 | -- |
Circuit/System Description
The stop lamp switch signal circuit is a direct hardwire input to the engine control module (ECM) from the body control module (BCM). The ECM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The BCM monitors the brake pedal position (BPP) sensor 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 BCM also sends a voltage signal on the stop lamp switch circuit to the ECM.
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 low voltage signal on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are applied.
Action Taken When the DTC Sets
| • | 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. |
| • | The ECM receives a CLEAR DTCs command from the scan tool. |
| • | A history DTC will clear once 40 malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Cruise Control Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector C1 of the ECM.
- Ignition ON, brake pedal applied, verify that a test lamp illuminates between the stop lamp switch signal circuit terminal 9 and ground.
- If all circuits test normal, replace the ECM.
| ⇒ | If the test lamp does not illuminate, test the stop lamp switch signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, test or replace the BCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM or ECM replacement, setup, and programming
