AutoCodes – Ford – P0504 2009 Ford Fusion

P0504 2009 Ford Fusion Code - Brake Switch Circuit 'A' / 'B' Correlation

Quick Answer

The Brake Pedal Switch (BPS) is sometimes referred to as the stop lamp switch. Common causes include Faulty Brake Pedal Switch (BPS) (Stop Lamp Switch), Faulty Brake Pedal Position (BPP) Switch, Brake Pedal Switch harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0504 2009 Ford Fusion indicates Brake Switch Circuit 'A' / 'B' Correlation.
Common causes: Common causes include Faulty Brake Pedal Switch (BPS) (Stop Lamp Switch), Faulty Brake Pedal Position (BPP) Switch, Brake Pedal Switch harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,180

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Basic DIY (1 / 3)

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Table of contents Created and updated by William Orellana on Jul 31, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0504 2009 Ford Fusion Description

The Brake Pedal Switch (BPS) is sometimes referred to as the stop lamp switch. The BPS provides a signal to the Powertrain Control Module (PCM) indicating the brakes are applied. The BPS is normally open and mounted on the brake pedal support. The Powertrain Control Module does a comparison test between the Brake Pedal Switch and the Brake Pedal Position (BPP) switch. The Diagnostic Trouble Code (DTC) will set when the BPS and BPP are no to factory specifications.

OBDII Code P0504 2009 Ford Fusion - Brake Switch Circuit 'A' / 'B' Correlation - AutoCodes.com — P0504 2009 Ford Fusion Code - Brake Switch Circuit 'A' / 'B' Correlation

What does this mean?

What are the Possible Causes of the DTC P0504 2009 Ford Fusion?

Faulty Brake Pedal Switch (BPS) (Stop Lamp Switch)
Faulty Brake Pedal Position (BPP) Switch
Brake Pedal Switch harness is open or shorted
Brake Pedal Switch circuit poor electrical connection

How to Fix the DTC P0504 2009 Ford Fusion?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0504 2009 Ford Fusion code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0504 2009 Ford Fusion code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0504 2009 Ford Fusion Code

1. What does the OBDII code P0504 mean on a 2009 Ford Fusion?

P0504 indicates a Brake Switch Circuit 'A' / 'B' Correlation issue, meaning the signals from the brake light switch circuits do not match as expected.

2. What are the symptoms of code P0504 in a 2009 Ford Fusion?

Common symptoms include the brake lights not working properly, the cruise control being disabled, and possible ABS or traction control system warnings.

3. What causes the P0504 code to appear on a 2009 Ford Fusion?

The most common causes are a faulty brake light switch, wiring issues like damaged or corroded connections, or a malfunctioning brake pedal assembly.

4. Can I drive my 2009 Ford Fusion with a P0504 code?

Itâ€™s not recommended to drive with this code active, as the brake lights may not function correctly, posing a safety risk to you and other drivers.

5. How do you diagnose a P0504 code on a 2009 Ford Fusion?

Diagnosing involves checking the brake light switch for proper operation, inspecting wiring and connectors for damage, and using a scan tool to monitor brake switch signal outputs.

6. How do I fix the P0504 code on my 2009 Ford Fusion?

Fixes include replacing the brake light switch if itâ€™s faulty, repairing damaged wiring or connectors, and ensuring the brake pedal is properly adjusted.

7. What tools are needed to troubleshoot a P0504 code?

Youâ€™ll need a multimeter to test electrical continuity, a scan tool to monitor live data, and basic hand tools for replacing the brake light switch.

8. How much does it cost to repair the P0504 code on a 2009 Ford Fusion?

Costs vary, but replacing a brake light switch typically ranges from $50 to $150, including parts and labor. Wiring repairs may cost more depending on complexity.

9. Can a blown fuse cause the P0504 code on a 2009 Ford Fusion?

While not a common cause, a blown fuse related to the brake light circuit could potentially trigger this code, so checking fuses is a good step.

10. Does the P0504 code affect the ABS or traction control systems?

Yes, the improper brake switch signals can interfere with the ABS or traction control systems, potentially disabling them and causing warning lights to illuminate.