1. Faulty Wiring: Check the wiring connections between the battery, alternator, and brake system. Ensure they are clean, tight, and free of corrosion. A loose or damaged wire can cause the light to come on.
2. Brake Fluid Level: Verify the brake fluid level in the master cylinder reservoir. If it's low, add brake fluid to the recommended level marked on the reservoir.
3. Brake System Issues: Inspect the brake pads and rotors for wear or damage. Worn-out brake pads or damaged rotors can trigger the brake light. Make sure the brake calipers and wheel cylinders are functioning correctly.
4. Charging System Problem: Despite replacing the alternator, there might still be an issue with the charging system. Check the voltage output of the alternator while the engine is running. It should be around 13.5 to 14.5 volts. If the voltage is too low or too high, the charging system may need further inspection.
5. Faulty Brake Light Switch: The brake light switch, which is activated when you press the brake pedal, might be defective. Check the switch for proper operation and replace it if necessary.
Since you've mentioned the light goes off when the car is idling and comes on when you press the gas pedal, it could be a problem with the voltage regulation system. To further diagnose the issue, it's recommended to take the vehicle to a qualified mechanic who can perform electrical tests and pinpoint the exact cause of the brake-battery light.
