Faulty Audi Headlight Switch Causing Random Light Issues

Had a similar electrical problem with my 2005 Audi A3 last year. Have some experience working on basic car maintenance, but electrical issues always need professional attention. The symptoms were nearly identical, dashboard lights acting up and the headlight switch was definitely not working properly. The dimmer switch felt particularly loose, just like you described. Took it to a workshop where they ran a full diagnostic on the lighting system. Turned out the main issue was a faulty connection in the automotive switch assembly. The cable harness connecting to the light switch had worn out, causing intermittent contact. They had to replace the entire connector and reseat the wiring. Total cost was 95 Euro for parts and labor. Before throwing parts at the problem, you should have a proper diagnosis done. Would really help if you could share: Do the lights turn on out of nowhere while driving or only when parked? Does the problem occur more frequently in wet weather? Are there any other electrical issues with the car? Have you noticed any correlation with using specific functions like the dimmer switch? This information would help determine if your issue matches what I experienced or if it might be something else in the system.

Last service done at 63500 KM / 3 months ago. The tail lights issue has persisted since then. Thanks for the detailed response about the switch assembly. My light switch triggers happen mostly while driving, not when parked. No correlation with wet weather noticed. The dimmer switch definitely feels loose and makes a clicking sound when adjusted. No other electrical problems present. After reading about the cable harness, I checked connections around the light switch assembly more carefully. Found some visible wear on the wiring near the connector, which likely points to a similar issue as yours. Will have it properly diagnosed rather than just replacing parts out of nowhere. Did your repair hold up well afterward? Also curious about labor time for the fix.

Good to hear you inspected the wiring, that visible wear around the connector matches exactly what my mechanic found. The repair has been solid for 14 months now with no electrical problems or lighting issues recurring. The labor time was relatively quick, about 1.5 hours total. Most of that time went into properly routing the new cable harness and ensuring all connections were secure. The automotive switch itself was straightforward to replace once they had access to the assembly. That clicking sound from your dimmer switch is a telltale sign. My switch made the same noise before failing completely. The wear on the harness often starts affecting the dimmer function first before causing broader issues with the tail lights and other lighting components. Since your car has similar mileage to when mine failed, and the symptoms match so closely, I strongly suspect the same root cause. The fuse box usually isnt the culprit with these progressive failure patterns, its typically the wiring or switch assembly itself. Quick tip: While waiting for the repair, try not to adjust the dimmer switch too much, as this can accelerate the wear on already damaged wiring. The complete fix with parts and labor should run about 100 Euro-150 Euro depending on whether they need to replace just the harness or the full switch assembly.

Thanks for clarifying about the service history and additional symptoms. Based on the clicking sound and visible wiring wear, it does seem my issue matches yours closely. Good call on examining the cable harness, finding that wear near the connector saved me from blindly replacing parts. The unusual light activation while driving concerns me most, especially since the dashboard lights keep showing warnings. At least the tail lights and other electrical systems still work normally, even with the loose dimmer switch. Given the similarities to your case and the 1.5 hour repair time you mentioned, I will schedule a proper diagnostic. The 100 Euro-150 Euro estimate helps set expectations for the repair costs. Will avoid adjusting the dimmer switch meanwhile to prevent further damage to the wiring. Just booked an appointment for next week. Hope the repair proves as durable as yours, 14 months without any lighting system issues sounds promising. Really appreciate the detailed information about your experience, helped confirm this likely needs a new cable harness rather than just a switch replacement.