Interior lighting / door lights defective (for Golf IV / Bora) (Solution)

In my Bora 1J6, the interior lighting, including the door indicator lights, has completely failed. After a long search, I found the culprit. In the wiring harness that runs along the A-pillar, several blue/red wires were crimped together. This "connection point" had completely disintegrated (with green corrosion). The "connection point" is completely embedded within the wiring harness, which is why the problem isn't visible from the outside.

Hi, thanks for the information! Could water be getting in somewhere, perhaps from a windshield that wasn't installed correctly?

Some time ago, the water tank was leaking. I'm not sure if this is related to the current issue, or if it's due to the humidity and salt buildup in the footwell, especially during the winter months.