2022-2024 Audi e-tron GT Third Brake Light Inoperative TSB

Owners of 2022-2024 Audi e-tron GT and RS e-tron GT models may experience an inoperative third brake light. This issue, which affects the high-mount brake light, is addressed by Audi Technical Service Bulletin (TSB) 2074275/1, issued on July 5, 2024. If your Audi e-tron GT third brake light is not working, this TSB provides the diagnostic and repair information.

Symptoms

The primary symptom reported by owners is that the "Customer states the 3rd brake light does not work." This means the high-mounted brake light, typically located at the top of the rear window, fails to illuminate when the brakes are applied.

Fault Codes / DTCs

When the third brake light is inoperative, technicians may find the following Diagnostic Trouble Code (DTC) stored in the Comfort System Central Control Module -J393- (address word 0046):

• DTC B12C615: "Bulb for high-mount brake light Open circuit/short circuit to B+ (Active/Passive)"

This DTC indicates an electrical problem with the high-mount brake light circuit, either an open circuit (break in wiring) or a short circuit to the positive voltage supply.

Technical Background

Audi has identified that the printed circuit located along the top of the rear glass, which is integral to the third brake light system, can be susceptible to damage from corrosion. This corrosion can lead to electrical malfunctions, causing the third brake light to become inoperative.

Repair Procedure Summary

The repair outlined in TSB 2074275/1 involves installing an adapter harness to bypass the problematic circuit on the rear glass. The general steps are:

1. Accessing the Brake Light: Remove the seat belt feeder trim, C-pillar trim, and rear shelf to gain access to the third brake light. Figure 1 in the TSB illustrates the trim pieces to be removed.
2. Removing the Brake Light: Unplug and remove the third brake light assembly (Figure 2).
3. Accessing the Connector: Pull the foam-insulated connector for the third brake light circuit from behind the C-pillar (Figure 3).
4. Installing Adapter Harness: Separate the existing connection and insert the new adapter harness, part number 4J3 971 157, into the vehicle side of the wire harness only. The wires leading to the welded points on the glass will remain unused (Figure 4).
5. Insulating Connections: Wrap the unused connector end from the glass to the new harness. Insulate as needed to prevent noise and future chafing (Figure 5). Ensure enough length of the new harness is available for future installation/removal of the third brake lamp (Figure 6).
6. Routing and Securing: Loosely route the replacement harness 4J3 971 157 along the space between the headliner and glass. Secure the harness to prevent noise and protrusion from behind the headliner (Figure 8).
7. Final Assembly: Remove the label from the new harness to reduce noise (Figure 7). Reassemble the vehicle in reverse order according to the workshop manual.

Required Parts and Tools

To perform this repair, the following specific parts are required:

• 4J3 971 157: Adapter harness (Quantity: 1)
• N 10592002: Cloth adhesive tape (Quantity: 1)
• Fasteners, bolts, nuts, and screws as needed, per the Repair Manual.

It is crucial to use only the parts listed in this TSB, as they may supersede other part numbers found in ETKA.

Warranty Information

This repair is covered under Audi's warranty for vehicles up to 48 months or 50,000 miles. For Certified Pre-Owned (CPO) vehicles, the G10 claim type applies, and owner verification is required. If the vehicle is outside of any warranty, this Technical Service Bulletin serves as informational guidance only. The Service Number for this TSB is 9470, and the Damage Code is 0040. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.

What Owners Should Know

If your Audi e-tron GT third brake light is not functioning, contact your authorized Audi dealership. They will diagnose the issue, confirm the presence of DTC B12C615, and perform the repair as outlined in TSB 2074275/1. This repair involves replacing the problematic circuit with an adapter harness to restore proper function to the high-mount brake light.

Source: NHTSA ID: 11005923, TSB 90 24 12 2074275/1