P0571 Cruise Control / Brake Switch Circuit Malfunction

DTC P0571 - OBD-II Data Sheet

Cruise Control / Brake Switch A Circuit Malfunction

What does trouble code P0571 mean?

This is a generic powertrain diagnostic trouble code (DTC) and is commonly applied to OBD-II vehicles. Car 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 operation of the engine, but also makes sure that our creatures are working normally (like cruise control).

There are many factors that can change the speed of your vehicle while driving on the road. Some of the newer Adaptive Cruise Control (ACC) systems actually adjust the vehicle's speed based on the environment (for example, overtaking, slowing down, lane departure, emergency maneuvers, etc.).

This is beside the point, this fault is related to a fault in the cruise control/brake switch "A" circuit. Proper operation of the brake switch is an essential part of the operation of your cruise control system. Considering the fact that one of the many ways to disable or disable cruise control is to press the brake pedal, you'll want to take care of that. Especially if you use cruise control on your daily commute. The letter designation in this case - "A" - can refer to a specific wire, connector, bundle, etc. E. To determine which one this code refers to, you will need to check the appropriate service manual from the manufacturer. If you're having a hard time finding what you need, it's always a good idea to look up a wiring diagram for your cruise control system. These diagrams, a lot of the time, can provide you with valuable information (sometimes location, specs, wire colors, etc.)

P0571 Cruise / Brake Switch A Circuit Malfunction and related codes (P0572 and P0573) are set when the ECM (Engine Control Module) detects a malfunction in the cruise / brake switch "A" circuit.

Example of a brake switch and its location:

What is the severity of this DTC?

Typically, with cruise control systems, the severity is set to low. But in this case, I'll go for medium-heavy. The fact that this malfunction can cause the brake switch to malfunction, or vice versa, is of great concern.

One of the other functions of your brake switch is to signal the rear brake lights on to inform other drivers of your deceleration/braking. However, this operation is very important when considering the overall safety of the driver.

What are some of the symptoms of the code?

Symptoms of a P0571 diagnostic code may include:

• Cruise control does not work completely
• Unstable cruise control
• Some features do not work as expected (e.g. install, resume, speed up, etc.)
• Cruise control turns on but does not turn on
• No brake lights if brake light switch is faulty

What are some of the common causes for the code?

Reasons for this P0571 cruise control code may include:

• Faulty cruise control / brake switch
• Wiring problem (e.g. pinched brake pedal, chafing, etc.)
• ECM (Engine Control Module) problem (such as internal short circuit, open circuit, etc.)
• Debris / dirt mechanically interferes with the operation of the brake switch
• Brake switch not adjusted properly
• Brake switch outside its mount

Is code P0571 critical?

Not on my own.

The P0571 error code only indicates minor problems and rarely creates drivability problems. In the worst case, your car's cruise control simply won't work. 

But code P0571 may appear with other codes that indicate more serious problems with the brake pedal, brake switch, or cruise control system. 

P0571 can also appear with codes such as DTC P1630 which is related to the skid control ECU or DTC P0503 which is related to the speed sensor car. 

Problems with these units can lead to more serious road safety problems.

What are some of the steps to troubleshoot a P0571?

The first step in the process of troubleshooting any problem is to review technical service bulletins (TSBs) for known problems with a particular vehicle.

Advanced diagnostic steps become very vehicle specific and may require appropriate advanced equipment and knowledge to be performed accurately. We outline the basic steps below, but refer to your vehicle / make / model / transmission repair manual for specific steps for your vehicle.

Basic step # 1

The first thing I would do in this case would probably look under the dashboard and immediately glance at the brake switch. It is usually attached to the brake pedal lever itself. From time to time, I've seen a driver's foot completely break the switch from its mount, so I mean if it's not installed properly and / or is completely broken, you can tell right away and potentially save time and save time and commissions.

So, if so, I would recommend replacing the cruise / brake switch 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 even causing additional problems.

Basic step # 2

Check the circuit involved. Refer to the Wiring Diagram in your service manual to determine the color coding and designation of the cruise control/brake switch A circuit. Often, 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. Using a multimeter, you can perform many tests. One common test is the integrity check. The specifications provided by the manufacturer are necessary to compare actual values ​​with those desired. Generally speaking, you will be testing the resistance of a particular circuit to determine if there are open circuits, high resistance, etc. If you are doing this test, it would be a good idea to check the pins in the connectors, the switch, and the ECM. Sometimes moisture can get in and cause intermittent connections. If there is corrosion, remove it with an electrical cleaner before reconnecting.

Basic step # 3

Take a look at your ECM (Engine Control Module). It is important to note that sometimes when cruise control is used, it is the BCM (Body Control Module) that monitors and regulates the system. Determine which one your system uses and inspect it for water intrusion. Anything fishy? take the vehicle to your reputable store / dealer.

What is P0571 Engine Code [Quick Guide]

5 Frequently Asked Questions About Diagnostic Codes

Here are answers to some additional questions you may have:

1. What is a fault code?

A Diagnostic Trouble Code (DTC) is a code generated by a vehicle's on-board diagnostic (OBD) system to diagnose vehicle problems. 

2. What is ECM?

The Engine Control Module (ECM), also known as the Powertrain Control Module (PCM), monitors and controls all kinds of sensors and switches related to the operation of your vehicle's engine. This includes the cruise control function, which controls the vehicle's speed, or the skid control ECU, which controls traction.

3. What is a generic fault code?

"Generic" means the DTC will point to the same problem for different OBD-II vehicles independently of brands. 

4. What is a brake switch?

The brake switch is connected to brake pedal and is responsible for deactivating the cruise control system, as well as controlling the brake light. 

The brake switch is also known as:

• Brake light switch
• Brake light switch
• Brake light switch
• Brake switch

5. How does the brake switch circuit work?

The engine control module (powertrain control module) monitors the voltage on the brake switch circuit (stop light circuit). 

When you depress the brake pedal, voltage is applied to the "STP terminal" in the ECM circuit through the brake light switch assembly. This voltage at the "STP terminal" signals the ECM to disable the cruise control. 

When you release the brake pedal, the brake light circuit reconnects to the ground circuit. The ECM reads this zero voltage and determines that the brake pedal is free.

Need more help with the P0571 code?

If you still need help with DTC P0571, post a question in the comments below this article.

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