Experiencing problems with your Mk5 Gti Rear Lights can be frustrating and a safety concern. It’s not uncommon for owners to encounter situations where multiple rear lights, such as the brake light, turn signal, and even license plate bulbs, suddenly stop working. Let’s delve into a common scenario and explore a likely cause, focusing on how to diagnose and potentially resolve these MK5 GTI rear lights malfunctions.
One MK5 GTI owner reported a sudden issue where the rear right brake light and turn signal, along with the license plate bulbs, all failed simultaneously. Naturally, the first step was to replace the bulbs, but unfortunately, this didn’t solve the problem. Checking the fuses also proved fruitless, leaving the owner puzzled about the cause of the MK5 GTI rear lights outage.
When multiple lights on one side of your MK5 GTI malfunction at the same time, especially those related to the rear right, the wiring harness becomes a prime suspect. A damaged wiring harness on the right side of the car can easily explain why the brake light, turn signal, and license plate lights are all affected. This is because the license plate light connections are integrated into the same right-side wiring harness that powers the other rear lights.
According to an experienced VW technician, the wiring harness in question originates at the Vehicle Electrical System Controller J519, then routes through the dashboard, down the right A-pillar, and along the floor under the carpet. For a 2-door MK5 GTI, it continues behind the side panel in the rear seat to reach the back of the car. This extensive routing means the harness is potentially vulnerable to damage at various points along its path.
MK5 GTI wiring harness location diagram showing junction for tail light and license plate wires.
The image above illustrates a critical junction point where the tail light wires branch off from the license plate light wires within the harness. If you’re experiencing a similar issue with your MK5 GTI rear lights, this area, or just forward of it, is a good place to start your inspection.
Accessing this section of the wiring harness can be somewhat challenging. As shown in the following images, reaching the harness “by the book” might involve removing interior trim panels to gain proper access.
Location of MK5 GTI wiring harness behind the plastic side cover in the rear of the car.
Accessing the MK5 GTI wiring harness junction – interior trim removal.
MK5 GTI interior trim components removed to access wiring harness.
While the process might seem daunting, understanding the path of the wiring harness is crucial for effective troubleshooting.
MK5 GTI wiring harness floor channel location – fuel pump wires identification.
The final image highlights the floor channel where the harness runs. Notably, the fuel pump wires are also located in this area. However, if only your rear lights are affected, the damage is more likely to be located further towards the rear of the car, beyond where the fuel pump wires branch off.
In conclusion, if you’re facing a situation where your MK5 GTI rear lights, specifically the right brake light, turn signal, and license plate lights, are all out despite replacing bulbs and checking fuses, a damaged right-side wiring harness is a highly probable cause. Careful inspection of the harness, particularly in the rear passenger side area, is the next logical step in diagnosing and resolving this issue.
