Technical Description of OBD-II Trouble Code
The circuit for Cruise Control/Brake Switch A is experiencing low voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) that applies to OBD-II vehicles, including Chevrolet, GMC, VW, Audi, Dodge, Jeep, Volkswagen, Volvo, Peugeot, Ram, Chrysler, Kia, Mazda, Harley, Cadillac, etc.
The engine control module (ECM) and other modules not only monitor various sensors and switches related to the engine’s proper functioning, but they also ensure that our creature comforts, such as cruise control, are operational.
While driving, there are many factors that can affect the speed of your vehicle. Some adaptive cruise control (ACC) systems adjust vehicle speeds based on the surrounding conditions, such as passing, slowing for traffic, lane departure, emergency maneuvers, etc.
However, in this case, the fault refers to a malfunction in the cruise control/brake switch “A” circuit. The brake switch plays a crucial role in the operation of the cruise control system. Since depressing the brake pedal is one way to disable or turn off cruise control, it is important to address this issue, especially if you use cruise control regularly. The letter designation “A” may refer to a specific wire, connector, harness, etc. To determine the exact component associated with this code, consult the appropriate manufacturer-specific service manual or a wiring diagram for the cruise control system.
The P0572 Cruise Control/Brake Switch A Circuit Low and related codes (P0571 and P0573) are set when the ECM detects a low voltage condition within the cruise control/brake switch “A” circuit.
Example of a brake switch and its location:
What is the severity of this DTC?
Typically, the severity of cruise control system issues is considered low. However, in this case, it is moderately-severe due to the potential for the brake switch or cruise control to malfunction.
One of the important functions of the brake switch is to activate the rear brake lights, which inform other drivers of your deceleration or braking. Therefore, the proper operation of the brake switch is crucial for overall driver safety.
What are some of the symptoms of the code?
Symptoms of a P0572 diagnostic code may include:
What are some of the common causes of the code?
Possible causes for this P0572 cruise control code may include:
What are some P0572 diagnostic and troubleshooting steps?
The first step in troubleshooting any malfunction is to consult the Technical Service Bulletins (TSB) for known issues with the specific vehicle.
Advanced diagnostic steps are highly vehicle-specific and may require specialized equipment and knowledge. The following are basic steps, but refer to a vehicle-specific repair guide for detailed instructions.
Basic Step #1
Inspect the brake switch located under the dash, mounted to the brake pedal arm. If the switch is broken or improperly mounted, replace it with a new one following the manufacturer’s instructions to avoid further issues.
Basic Step #2
Verify the circuit involved by referring to a wiring diagram in the service manual. Disconnect one end of the circuit from the brake switch and the other end from the ECM. Use a multimeter to perform tests, such as a continuity test, to check for any opens or high resistance. Inspect the pins in the connectors, switch, and ECM for corrosion and clean if necessary.
Basic Step #3
Inspect the ECM or BCM (body control module) responsible for monitoring and adjusting the cruise control system. Look for signs of water intrusion and consult a reputable shop or dealer if any issues are suspected.
