P0504 - OBD II Trouble Code

Our automotive experts have put together the following information about the P0504 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0504 code.

What Does P0504 Code Mean?

OBD-II Code P0504 is defined as a Brake Switch "A"/"B" Correlation

The Brake Switch tells the engine control module (PCM) that the brake pedal is depressed. This switch also controls the brake lights. If the PCM detects an incorrect signal from the Brake Switch, the PCM will set code P0504.

P0504 Symptoms

• Brake lights may not illuminate
• Cruise control will not operate

Common Problems That Trigger the P0504 Code

• Brake switch failure
• Powertrain Control Module (PCM) failure
• Wiring issue