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: Brake Switch Circuit 1 Low VoltageDTC P0573: Brake Switch Circuit 1 High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Stop Lamp Switch Signal | B3445, P0573 | P0573 | P0572 | -- |
Circuit/System Description
When the brake pedal is applied, the BCM receives a brake applied signal from the brake pedal position sensor (BPPS). The BCM applies B+ to the stop lamp switch signal circuit. This circuit supplies a B+ signal to the powertrain control module (PCM) (V6), engine control module (ECM) (V8), transmission control module (TCM) (V8), throttle actuator control (TAC) module (V6), and electronic brake control module (EBCM) indicating the brakes are applied. B+ is also supplied to the center high mound stop lamp (CHMSL), illuminating it when the brakes are depressed.
Conditions for Running the DTC
The ignition is ON
Conditions for Setting the DTC
P0572
The ECM/PCM detects a short to ground or an open/high resistance on the stop lamp switch signal circuit while the brakes are applied
P0573
The ECM/PCM detects a short to voltage on the stop lamp switch signal circuit while the brakes are not applied
Action Taken When the DTC Sets
| • | Stop lamp switch input is ignored. Brake apply status is obtained through serial data messages. |
| • | Cruise control is disabled |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists |
| • | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Verification
Ignition ON, depress the brake pedal. The stop lamps should illuminate.
Circuit/System Testing
- Ignition OFF, disconnect the X1 harness connector at the ECM/PCM.
- Connect a test lamp between the signal circuit terminal 32 and ground.
- Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when pressing and releasing the brake pedal.
- If all circuits test normal, replace the ECM/PCM.
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM, ECM, or PCM replacement, setup, and programming
