Audi A6 Brake Light Fail - How To Diagnose And Fix

By Nick Marchenko, PhD

Experiencing brake light failure in your Audi A6 can be both frustrating and dangerous. To ensure your vehicle's safety and functionality, we've compiled a thorough DIY guide, based on real-world troubleshooting and solutions from various Audi A6 owners who faced similar issues. This guide is designed to help you identify and solve brake light problems in your Audi A6, incorporating a variety of checks and fixes.

Preliminary Checks

Before diving into the more detailed troubleshooting steps, perform these preliminary checks:

• Fuse Inspection: Verify that the fuses related to the brake lights are intact. A blown fuse can often cause the brake lights to stop working.
• Check All Brake Lights: Confirm that all brake lights, including the third brake light, are not working to rule out bulb failure.

Troubleshooting Steps

Step 1: Test the Brake Lights

• External Battery Test: Use an external 12V or 9V battery to test if the brake lights illuminate when not connected to the car. This can help determine if the issue is with the lights themselves or with the power supply.

It is best to have a couple of spare bulbs in the car in case one burns out on the road. For more information on bulbs for your Audi A6, see the chart below:

• 2015;
• 2014;
• 2013;
• 2012;
• 2011;
• 2010;
• 2009;
• 2008;
• 2007;
• 2006;
• 2005;

Step 2: Inspect the Brake Light Switch

• Location and Inspection: The brake light switch is located near the brake pedal. Check if it's properly adjusted or if it has failed.
• Replacement: If suspected to be faulty, replace the brake light switch. It's an inexpensive part and fairly easy to replace. Make sure to use OEM parts for better compatibility and performance.

Step 3: Electrical Connections and Wiring

• Connector and Wiring Check: Inspect the connectors and wiring to the brake lights for any signs of oxidation, corrosion, or damage. Clean or replace connectors as needed.
• Oxidized Connectors: If connectors are oxidized, clean them thoroughly and apply dielectric grease to prevent future corrosion.

Step 4: Voltage and Resistance Checks

• Voltage Test: Use a multimeter to check for voltage at the brake light connectors when the brake pedal is pressed. No voltage indicates a problem upstream.
• Smart Computer Check: Be aware that some Audi models have a smart computer that checks the resistance in the brake light circuit. If resistance is out of specification, it may stop sending voltage. This can be a tricky issue as it might show voltage initially and then stop.

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Step 5: Additional Considerations

• Weather Seal and Water Damage: Ensure the weather seal on the brake light assembly is intact to prevent water ingress which can lead to connector oxidation.
• Rear Wiper Water Pipe: Check the rear wiper water pipe for breaks, as it can contribute to moisture problems affecting the lights.

Step 6: OEM Light Assembly Replacement

If all else fails, consider replacing the brake light assembly with an OEM part. It can be a more straightforward solution if troubleshooting doesn’t resolve the issue.
Installation Tips for Brake Light Switch

• When installing a new brake light switch, do not manipulate or compress the plunger before installation. The switch should auto-adjust to the correct distance once installed.
• Avoid using excessive force to avoid damaging the switch.

Final Thoughts

Fixing brake light failure in an Audi A6 can range from simple bulb replacement to more complex electrical troubleshooting. It's crucial to approach the process methodically, checking from the simplest solutions to more involved ones. Remember, safety is paramount. If you're unsure about any step or if the problem persists, consulting a professional or an experienced mechanic is advisable.

By following this comprehensive guide, you should be able to diagnose and fix brake light issues in your Audi A6, ensuring your vehicle remains safe and legal on the road.

See Also:

• Audi 3.0 TDI Engine Problems - Is It Good?
• Here Are The 5 Audi A6 Years to Avoid
• Cars Like Audi A6? 19 Similar Vehicles Worth Checking Out
• What Engines Can You Put in Audi A6?

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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