P0571: Cruise Control / Brake Switch A Circuit Malfunction

What does code P0571 mean? And how do you resolve it?

In this article, we’ll explain what the P0571 code is, its possible causes, and an easy way to resolve it.

What Is Code P0571?

P0571 is a generic OBD-II diagnostic trouble code (DTC) that the engine control module (ECM) generates. The P0571 code is defined as a “cruise control / brake switch ‘ A’ circuit malfunction.”

The letter ‘A’ can refer to a specific wiring, harness, connector, and so on.

Your mechanic would have to look up the vehicle service manual and wiring diagram to know what component is linked to the ‘A.’

What Does The P0571 Code Mean?

The P0571 code occurs when the engine control module detects a malfunction in the brake switch circuit and deactivates the cruise control.

What Can Trigger Code P0571?

An electrical malfunction usually triggers the P0571 code, but it can be prompted by something as simple as dirt on a connector, even if the rest of the brake switch is working fine.

Here are some common culprits:

A fault within the brake switch circuit, like a wiring issue.
A defective brake switch connector.
A faulty switch in the cruise control system buttons.
An internal short or open circuit in the engine control module.
A blown fuse (this can be a cause or symptom of the P0571 code).
Wrong brake light bulb installed.

Next, what kind of symptoms can you expect with a P0571 code?

Symptoms Associated With The P0571 Code

Here are several symptoms that are associated with a P0571 DTC:

The check engine light turns on.
Erratic cruise control functioning.
Some cruise control functions aren’t working correctly (like Set, Acceleration, or Resume).
The brake light doesn’t work due to problems with the brake light switch assembly.

Some of these symptoms may not only be related to the cruise control or brake switch.

For example, a glowing check engine light can imply different problems, ranging from a lean fuel mix to ABS issues.

That’s why it’s essential to get a professional opinion from a mechanic and have your stop lamp switch problem resolved correctly.

Is Code P0571 Critical?

Not by itself.
The P0571 error code only indicates minor issues and rarely creates driveability problems. At its worst, your vehicle cruise control simply won’t work.

But, the P0571 code may turn up alongside other codes that indicate more serious problems with the brake pedal, brake switch, or cruise control system. The P0571 can also turn up with codes like the P1630 DTC, which is related to the skid control ECU, or the P0503 DTC, which concerns the vehicle speed sensor.

Problems with these units can lead to bigger road safety issues.

How Is Code P0571 Resolved?

Your mechanic will review every error code present with an OBD-II scanner, including those on the freeze frame data. They’ll then clear the code and take your car for a test drive to see if the code returns.

If the code does return, your mechanic will need to investigate further. They’ll measure the voltage on each fuse or circuit to pinpoint the issue.

Once they’ve located the problem, your mechanic will repair or replace the faulty component, connector, or wiring. They’ll then reset the engine trouble code and take the vehicle for another test drive.

But what’s the best way to get all of this fixed?

The Best Way To Fix P0571 Code Issues

It’s a good idea to always get an experienced mechanic to diagnose your P0571 code and fix the issues associated with it.

When looking for a mechanic to deal with your P0571 code, make sure that that they:

Are certified.
Use only high-quality replacement parts and tools.
Offer a service warranty.

Luckily for you, AutoNation Mobile Service ticks all those boxes.

AutoNation Mobile Service is a convenient mobile vehicle repair and maintenance solution, and here’s why you should go to them for a P0571 DTC diagnosis:

Any error code diagnoses and fixes can be performed right in your driveway.
Online booking is convenient and easy
Competitive, upfront pricing
Expert technicians perform the vehicle inspection and servicing
All repairs and maintenance are done with high-quality equipment and replacement parts
AutoNation Mobile Service provides a 12-month | 12,000-mile warranty for all repairs

How much can you expect it to cost?

Depending on location, AutoNation Mobile Service typically charges between $95-$150 for a diagnosis. If you decide to follow through with the repair, the diagnosis fee will be applied to the final cost of the repair.

The cost to replace your brake light switch can range anywhere from $50-$160. The total price depends on a few different factors, including your location, make and model of your vehicle, and even your engine type.

Now that we’ve gone over the basics of code P0571, let’s cover some FAQs:

5 FAQs About Diagnostic Codes

Here are the answers to some additional questions you may have:

1. What’s a DTC?

The diagnostic trouble code (DTC) is a code generated by a vehicle’s onboard diagnostics (OBD) system to identify vehicle malfunctions.

2. What’s The ECM?

The engine control module (ECM), also known as the powertrain control module (PCM), monitors and controls all sorts of sensors and switches related to the engine functionality of your vehicle. This includes the cruise control function that manages vehicle speed or the skid control ECU that manages traction.

3. What Is A Generic Trouble Code?

“Generic” means that the trouble code will indicate the same issue across different OBD-II vehicles regardless of make.

4. What Is The Brake Switch?

The brake switch is connected to the brake pedal and is responsible for deactivating the cruise control system and also controls the brake light.

The brake switch is also known as the:

Brake light switch
Stop light switch
Stop lamp switch
Brake release 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 signal circuit).

When you depress the brake pedal, voltage is delivered to the “terminal STP” in the ECM circuit through the stop light switch assembly. This voltage on the “terminal STP” gives a signal to the ECM to cancel the cruise control.

When you release the brake pedal, the stop light signal circuit is reconnected to the ground circuit. The ECM reads this zero voltage and recognizes that the brake pedal is free.

Final Thoughts On Code P0571

Troubleshooting a DTC can be a complex process, so it’s much easier to get a professional to do it. Having no cruise control may not be a big deal on its own, but you’d want to make sure there aren’t any related issues complicating things.

For an easy solution, just contact AutoNation Mobile Service, and expert technicians will be at your door, ready to help in no time!