How to Fix Audi TT RS Brake Light Fail: A DIY Guide

By Nick Marchenko, PhD

If you've discovered that your Audi TT RS brake lights have stopped functioning, this comprehensive DIY guide will walk you through troubleshooting and fixing the problem yourself. Whether it's a faulty brake light switch, a blown fuse, or wiring issues, we've got you covered.

Step 1: Check the Fuse

• Locate the Fuse Box: The brake light fuse in an Audi TT RS is typically located at the right side end of the dash, contrary to what the manual might indicate.
• Inspect Fuse 13: This is specifically for the brake lights. If it's blown, replace it with a new one of the same rating.

Step 2: Inspect and Replace the Brake Light Switch

• Locate the Switch: The brake light switch is generally positioned near the brake pedal. You might need to remove the lower dash panel to access it.
• Check the Switch: If your brake lights are unresponsive, the switch might be faulty. Remove the switch and check for dirt or damage.
• Replace If Necessary: Brake light switches are affordable (around £8) and can be replaced without needing to re-code the ECU, despite what some dealers might suggest.
  • Installation Tip: It’s a twist-in unit. Make sure it’s set correctly as per installation instructions found online.
  • Note: Some users have mentioned needing to remove a ratchet from the switch before installation.

Step 3: Check the Brake Light Bulbs and Sockets

• Examine the Bulbs: Ensure that all brake light bulbs are functioning and both filaments are intact.
• Look at the Socket: Sometimes, issues occur due to poor connections at the bulb socket. Check for any burnt or corroded pins.
  • Possible Solution: Adding an extra ground to the bulb holder can sometimes resolve connection issues.

If your brake light bulbs are not functioning as they should - maybe it's time to consider a replacement. To finde the proper brake light bulbs for your Audi TT RS - consult the chart below:

• 2021;
• 2020;
• 2019;
• 2018;
• 2013;
• 2012;

Step 4: Additional Electrical Checks

• Relay and Additional Fuses: If the above steps fail, check other related fuses and relays (like the main relay for brake lights under the dash). Ensure no other electrical components (like fog lights) are affected, which could indicate a broader electrical issue.
• Listen for Clicking Noises: A clicking sound from the battery area when the brake pedal is pressed can suggest a relay fault.
• Inspect Wiring Connections: Ensure all electrical connections, especially at ground points, are clean and secure.

Step 5: Visit a Professional If Needed

If after all these steps your brake lights still fail to operate, it might be time to consult with a professional. Electrical issues in vehicles can be complex and sometimes require specialized diagnostic tools and expertise.

Final Tips

• Purchase Quality Parts: Opt for higher-quality switches and bulbs to avoid repeated failures.
• Regular Maintenance: Regularly check and maintain the vehicle’s electrical connections to avoid sudden failures.
• DIY Resources: Utilize forums and online resources for specific installation guides and tips.

By following these steps, you can address common issues related to brake light failures in an Audi TT RS, potentially saving time and money on professional repairs.

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.

Full profile → LinkedIn →