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 Descriptors
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 |
|---|---|---|---|---|
Ignition Voltage | P0572 | P0572 | -- | -- |
Stop Lamp Switch Signal | P0572 | P0572 | P0573 | -- |
Circuit/System Description
The TCC Brake signal circuit is a high voltage input to the body control module (BCM), engine control module (ECM), transmission control module (TCM), Power Take Off (PTO) module (if equipped) and Trailer Brake controller (if equipped). The BCM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The ECM monitors the TCC Brake signal to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a serial data message to the ECM indicating that the brake pedal has been applied. The ECM senses a high voltage signal on the brake switch signal circuit when the stop lamp switch is closed.
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 TCC brake signal circuit for more than 2 seconds when the serial data message from the BCM indicates the brakes are applied. The ECM sets the DTC when the condition has been detected 8 out of 10 times.
P0573
The ECM detects a high voltage signal on the TCC brake signal circuit for more than 2 seconds when the serial data message from the BCM indicates the brakes are released. The ECM sets the DTC when the condition has been detected 8 out of 10 times.
Actions Taken When the DTC Sets
| • | The cruise control system becomes disabled. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | A history DTC will clear after 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
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the stop lamp switch.
- Ignition ON, test for B+ between the B+ circuit terminal B and ground.
- Verify the BPP Circuit Signal data parameter displays released.
- Connect a 3A fused jumper between the B+ circuit terminal B and the signal circuit terminal A. Verify the BPP Circuit Signal data parameter displays applied.
- If all circuits test normal, test or replace the stop lamp switch.
| ⇒ | If less than the specified value, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If not the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the stop lamp switch.
- With the brake pedal released, test for infinite resistance between terminal A and terminal B at the stop lamp switch.
- With the brake pedal released, test for less than 1.0 ohm between terminal C and terminal D at the stop lamp switch.
- With the brake pedal applied, test for less than 1.0 ohm between terminal A and terminal B at the stop lamp switch.
- With the brake pedal applied, test for infinite resistance between terminal C and terminal D at the stop lamp switch.
| ⇒ | If not the specified value, replace the stop lamp switch. |
| ⇒ | If not the specified value, replace the stop lamp switch. |
| ⇒ | If not the specified value, replace the stop lamp switch. |
| ⇒ | If not the specified value, replace the stop lamp switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
