What does it mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and generally applies to OBD-II vehicles. Vehicle brands may include, but are not limited to, Chevrolet, GMC, VW, Audi, Dodge, Jeep, Volkswagen, Volvo, Peugeot, Ram, Chrysler, Kia, Mazda, Harley, Cadillac, etc.
The ECM (Engine Control Module), among many other modules, not only monitors the various sensors and switches involved in the proper functionality of the engine but also ensures to maintain the comfort of our creatures in place (e.g., cruise control).
Many factors can alter your vehicle’s speed when driving on the road. Some of the new adaptive cruise control (ACC) systems actually adjust vehicle speeds based on the environment (e.g., overtaking, slowing traffic, lane departure, emergency maneuvers, etc.).
Beyond the point, with this fault, they refer to the malfunction of the cruise control/brake switch “A” circuit. The proper operation of the brake switch is an integral part of your cruise control’s function. Since one of the many ways to deactivate or turn off cruise control is by pressing the brake pedal, you’ll want to address this. Especially if you use cruise control in your daily commutes. In this case, the designated letter – “A” – may refer to a specific wire, connector, harness, etc. To determine which one this code refers to, you will need to consult the appropriate manufacturer-specific service manual. If you’re having trouble finding what you need, it’s always a good idea to look for a wiring diagram for the cruise control. These diagrams can often provide valuable information (sometimes location, specifications, wire colors, etc.).
The P0573 cruise control/brake switch A circuit high and related codes (P0571 and P0572) are defined when the ECM (Engine Control Module) detects a malfunction in the cruise control/brake switch “A” circuit. In this case, it means there is a high electrical condition detected in the circuit.
Example of a brake switch and its location:
P0573 Brake Switch
How severe is this DTC?
Usually, with cruise control systems, I would say the severity is set to low. But in this case, I’ll go with moderately severe. The fact that there is a possibility this fault could cause a malfunction of the brake switch, or vice versa, is a significant concern.
One of the other functions of your brake switch is to provide the signal to turn on your rear brake lights to inform other drivers of your deceleration/braking. That said, its operation is quite important when considering overall driver safety.
What are some of the symptoms of the code?
Symptoms of a P0573 diagnostic code may include:
- Cruise control completely inoperative
- Erratic cruise control operation
- Certain functions not working as they should (e.g., set, resume, accelerate, etc.)
- Cruise control on but not engaging
- No brake lights if the brake light switch is faulty
What are some common causes of the code?
Causes of this P0573 cruise control code may include:
- Faulty cruise control/brake switch
- Wiring issue (e.g., pinched on the brake pedal, chafed, etc.)
- ECM (Engine Control Module) problem (i.e., internal short, open circuit, etc.)
- Debris/dirt mechanically interfering with the brake switch operation
- Misadjusted brake switch
- Brake switch out of its mount
What are the diagnostic and troubleshooting steps for P0573?
The first step in the troubleshooting process for any malfunction is to check the Technical Service Bulletins (TSBs) for known issues with the specific vehicle.
Advanced diagnostic steps become very vehicle-specific and may require the appropriate equipment and advanced knowledge to operate accurately. We include the basic steps below but refer to a repair guide specific to the year/make/model/powertrain for steps tailored to your vehicle.
Basic Step #1
The first thing I would do in this case is probably take a look under the dashboard and inspect the brake switch right away. It is usually mounted on the brake pedal arm itself. I’ve sometimes seen the driver’s foot completely knock the switch off its mount, so I mean if it’s not mounted properly and/or completely broken, you’ll be able to tell immediately and potentially save yourself time and shop fees.
So, that said, if that is the case, I would recommend replacing the cruise control/brake switch with a new one. Be sure to follow the manufacturer-specific installation and adjustment procedures for brake switches to avoid damaging the sensor or even causing more problems.
Basic Step #2
Check the affected circuit. Refer to a wiring diagram in your service manual to determine the color codes and circuit designation for the cruise control/brake switch A. Often, to rule out the possibility that the fault lies in the harness itself, you can disconnect one end at the brake switch and the other at the ECM. Using a multimeter, there are many tests you can perform. A common test is a continuity test. Specifications provided by the manufacturer are necessary to compare actual values to desired ones. Generally, you will check the resistance of the particular circuit to determine any open circuits, high resistances, etc., present. If you perform this test, it would be a good idea to inspect the connector pins, the switch, and the ECM. Sometimes, moisture can seep in and cause intermittent connections. If corrosion is present, use an electrical connection cleaner to remove it before reconnecting everything.
Basic Step #3
Take a look at your ECM (Engine Control Module). It’s important to note that sometimes with cruise control, it’s the BCM (Body Control Module) that monitors and adjusts this system. Identify which one your system uses and physically inspect for any water intrusion. Anything suspicious here? Take the vehicle to your reputable shop/dealer.