Fault code P0571 – cruise control/brake switch “A” circuit malfunction

Fault code P0571 is called “Cruise Control/Brake Switch “A” Circuit Malfunction” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0571

This Diagnostic Trouble Code (DTC) is a general powertrain code. Error P0571 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P0571 – cruise control/brake switch

The Engine Control Module (ECM), among many other modules, not only controls the various sensors and switches involved in proper engine operation. But it also makes sure that our systems are working properly (such as cruise control).

There are many factors that can change the speed of your vehicle as you drive down the road. Some of the newer Adaptive Cruise Control (ACC) systems actually adjust the speed of your car. Depending on your surroundings, such as overtaking, slowing down, getting out of your lane, emergency maneuvers, etc.

Proper operation of the brake switch, is integral to the operation of your cruise control system. Given the fact that one of the many ways to disengage the cruise control is to depress the brake pedal. Therefore, this error should be taken seriously. Especially if you use cruise control on everyday trips.

The letter designation, in our case “A” may refer to a specific wire, connector, wiring harness, etc. To determine which one this code refers to, you will need to check the appropriate service manual from the manufacturer.

Error P0571 – cruise control/brake switch “A” circuit failure, as well as related codes P0572, P0573. Set when the ECM (Engine Control Module) detects a fault in the “A” cruise control / brake switch circuit. In this case, it means that a high electrical voltage or resistance is detected in the circuit.

Symptoms of vehicle malfunctions

The main signal that an error P0571 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Cruise control does not work completely.
  2. Unstable operation of the cruise control.
  3. Some functions do not work as they should (e.g. setting, resuming, accelerating, etc.).
  4. Cruise control is engaged, but does not work.
  5. The brake lights do not work, but the brake light switch is defective.

The P0571 error itself is not serious, but this code may appear together with others. This occurs when there are serious problems with the brake pedal or cruise control.

Factors that can cause this error code

The error code P0571 can mean that one or more of the following problems have occurred:

  • Cruise control / brake switch defective.
  • Wiring problem (breakage, chafing, etc.).
  • Problem with ECM (Engine Control Module) (i.e. internal short circuit, breakage, etc.).
  • Debris/dirt is mechanically interfering with the brake switch.
  • Brake switch not adjusted correctly.
  • Brake switch is not properly secured.

How to fix or reset OBD-2 code P0571

Some suggested steps for troubleshooting and fix the error code P0571:

  1. Usually to eliminate the error P0571 you only need to repair or replace the damaged wires.
  2. It is not superfluous to check the connections.
  3. It may also be necessary to replace blown fuses.

Diagnose and repair of problems

The first step in the P0571 troubleshooting process is to review the Technical Service Bulletins (TSB). For known problems with a particular vehicle.

The advanced diagnostic steps become very specific to the vehicle and may require the proper advanced equipment and knowledge to perform accurately. The following are basic steps, but refer to your vehicle’s repair manual for specific steps for your vehicle.

Look under the dashboard and look at the brake switch. It is usually attached to the pedal lever itself. Sometimes, the driver’s foot can slide the switch off its mount if it is not properly installed.

If this is the case, the cruise control/brake switch must be replaced with a new one. Be sure to follow the manufacturer’s instructions for installing and adjusting the brake switch to avoid damaging the sensor or causing additional problems.

Check the electrical circuit. Refer to the wiring diagram in the service manual to do this. To determine the color coding and circuit designation “A” of the cruise control/brake switch.

To rule out the possibility of a fault in the harness itself, you can disconnect one end from the brake switch and the other end from the ECM controller. Using a multimeter, you can perform some tests.

One common one is a continuity test. The specifications provided by the manufacturer are necessary to compare the actual values with the desired values. Generally speaking, you will be checking the resistance of a particular circuit to determine if there are breaks, high resistance, etc.

If you are performing this test, it would be a good idea to check the contacts in the connectors, switch, and ECM. Sometimes moisture can get in and cause intermittent connections.

Take a look at your engine control module (ECM). It is important to note that sometimes when using cruise control, it is the body control module (BCM) that controls and regulates this system.

Determine which one your system uses and physically inspect it for water intrusion.

On which vehicles does this problem occur most frequently

Fault code P0571 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi (A6)
  • Cadillac
  • Chery (Kimo, Tiggo)
  • Chevrolet (Captiva, Cobalt)
  • Chrysler
  • Citroen (C4, C5)
  • Dodge (Caliber, Caravan, RAM)
  • Fiat (Albea, Doblo, Punto)
  • Ford (Fiesta, Focus, Fusion)
  • Geely (Emgrand)
  • Hyundai (Santa Fe)
  • Infiniti
  • Iveco
  • Jeep
  • Kia
  • Lifan (X60)
  • Mazda (6)
  • Nissan
  • Opel (Antara, Astra, Corsa, Meriva, Vivaro, Zafira)
  • Peugeot (107, 206, 307, 407)
  • Renault
  • Seat
  • Skoda (Fabia, Octavia)
  • Ssangyong
  • Toyota (Prius)
  • Volkswagen (Golf, Passat, Polo, Transporter)
  • Volvo (XC90)
  • Vortex (Tingo)

Fault code P0571 can sometimes be found with other errors. The most common are the following: P0016, P0019, P0098, P0422, P0432, P0500, P0504, P0700, P0716, P0732, P0733, P0734, P0746, P0842, P0882, P0957, P2121, P2714, B2610, C1241, U1900.


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