How To Fix BMW i8 Brake Light Malfunction - DIY Guide

By Nick Marchenko, PhD

Fixing a brake light failure in your BMW i8 can be a daunting task if you're not familiar with automotive electrical systems. However, with the right approach, tools, and a bit of patience, you can troubleshoot and resolve the issue yourself. This guide combines insights from various experiences to help you diagnose and fix brake light problems.

Required Tools and Materials

• Multimeter or test lamp (multimeter is preferred)
• Replacement brake light switch (if necessary)
• Screwdriver set
• Wire brush or sandpaper for cleaning connections
• Electrical contact cleaner

Safety First

Before you begin, ensure the vehicle is parked on a level surface, the engine is off, and the keys are removed from the ignition. Work in a well-lit and ventilated area.
Diagnosis and Repair Steps

Step 1: Preliminary Checks

• Inspect the Brake Light Bulbs: Sometimes, the simplest solutions are the correct ones. Check if the bulbs are burnt out and replace them if necessary.
• Check the Fuse: Consult your vehicle's manual to locate the fuse associated with the brake lights and inspect it for damage. Replace the fuse if it's blown.

If you are looking for replacement bulbs - check the chart below to ensure that you choosing the right product:

• 2020;
• 2019;
• 2017;
• 2016;
• 2015;

Step 2: Inspect the Brake Light Switch

The brake light switch is a common failure point that can cause the brake lights not to work:

• Locate the Brake Light Switch: It is usually found above the brake pedal.
• Remove and Inspect the Switch: Look for any signs of damage or wear. A malfunctioning switch may not activate the brake lights when the pedal is pressed.
• Test the Switch: Use a multimeter to check for continuity. With the switch activated (pedal pressed), there should be continuity. If not, the switch needs replacing.

Step 3: Check Electrical Connections

• Inspect the Wiring: Look for any signs of wear, damage, or loose connections. Pay special attention to the area around the brake light switch and the lights themselves.
• Clean Ground Connections: Use a wire brush or sandpaper to clean the ground connections. A poor ground can cause brake light issues.
• Ensure Tight Connections: Make sure all connectors are tight and secure. A loose spade connector at the switch was found to be the issue in one case.

Step 4: Test the Circuit

• Using a Multimeter: Check for voltage at the brake light socket. There should be power when the brake pedal is pressed.
• Test for Ground: Check the ground connection at the brake light socket with one lead on the hot wire and the other on the grounding tab of the socket.

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Step 5: Replace Faulty Components

If any components are found to be faulty during your checks (such as the brake light switch or any damaged wiring), replace them with new ones. Ensure to use OEM parts for best compatibility and performance.

Additional Tips

• Consider a Professional Diagnosis: If you're unsure about any steps or the problem persists, consulting with a professional mechanic is advisable.
• Check for Recalls: Some models may have recalls related to brake lights or electrical systems. It's worth checking with a dealership.

Conclusion

Troubleshooting brake light issues in your BMW i8 requires a methodical approach to identify and resolve the problem. By following these steps, most common issues can be diagnosed and fixed. Remember, if at any point you feel uncomfortable performing these tasks, seeking professional assistance is the best course of action.

Nick Marchenko, PhD

Industrial Engineer & Automotive Content Specialist

Nick writes in-depth guides on car clubs, engine specs, vehicle ownership, and modifications, combining engineering knowledge with automotive passion.

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