Here are a few things to consider and check:
1. Wiring: Inspect the wiring for any damage, corrosion, or loose connections, particularly in the areas related to the brake lights and the horn. Look for any frayed wires or broken connectors that may be causing a disruption in the electrical circuit.
2. Brake Light Switch: The brake light switch is responsible for activating the brake lights when the brake pedal is depressed. Check the brake light switch to ensure it is functioning correctly and making proper contact when the brake pedal is pressed.
3. Horn Relay: The horn relay is responsible for providing power to the horn when the horn button is pressed. Locate the horn relay and check for any signs of damage or corrosion. You can try replacing the horn relay to see if that resolves the issue.
4. Fuse Box: While you mentioned checking the fuses, it's worth reinspecting the fuse box to make sure that the fuses related to the brake lights and the horn are not blown. Sometimes a fuse may appear to be intact but may have a hairline crack or internal damage.
5. Ground Connections: Ensure that the electrical system has proper grounding. Check the ground connections to make sure they are clean and secure, as poor grounding can lead to electrical issues.
6. Electrical Harness: If the problem persists, it could be an issue with the electrical harness itself. The electrical harness connects various electrical components and can develop faults or damage over time. Inspect the harness for any issues and consider having a professional auto electrician look into it.
If you are not confident in troubleshooting electrical issues, it's best to take your vehicle to a qualified auto electrician or mechanic who can properly diagnose and repair the problem.
