How to repair P0504 trouble code?
2 Answers
P0504 trouble code can be resolved by contacting a professional technician or by driving smoothly to upshift in advance. Below is relevant knowledge about the P0504 trouble code: 1. Position and function of the brake switch: The brake switch is installed near the brake pedal. Its function is to control the brake lights and provide brake signals to the PCM to determine whether the vehicle is braking. 2. Structure principle and impact of the brake switch: When the brake pedal is pressed, the brake switch opens; when the brake pedal is released, the brake switch closes. The brake switch is divided into two groups: one is the brake light switch, which controls the brake lights; the other is the brake signal switch. If the brake switch malfunctions, the brake lights will not display normally, and it may also cause abnormal operation of the ABS and cruise control systems. For vehicles with automatic transmission, it may also prevent the gear from being shifted out of the P position.
When my car displayed the P0504 fault code, I was startled because it usually indicates a brake switch signal issue. As an everyday driver, I found this could affect the cruise control system, such as it not working on the highway. I first checked the brake lights and discovered one bulb had burned out. After replacing it, the fault code disappeared. If all bulbs are functioning, the issue might be a loose or corroded brake switch itself. You can test the resistance with a multimeter, but it's best to have a professional technician check the wiring to avoid unnecessary disassembly for minor issues. Actually, this fault is quite common, often caused by switch misalignment or wire aging, and regular maintenance can prevent it.
