Cadillac XT6 Light Switch Malfunction Causes Chaos

As someone with moderate DIY repair experience, I dealt with a very similar issue on my 2018 Cadillac XT5. The symptoms were nearly identical, with unpredictable behavior when using the headlight switch and flickering dashboard lights. After taking it to my trusted workshop, they diagnosed a faulty wiring connection at the main light switch assembly. The cable harness had developed a poor connection due to repeated use. While the dealer often suggests replacing the entire headlight switch unit, in my case it was just the wiring that needed attention. The repair involved cleaning the connector pins and replacing a damaged section of the wiring harness. Total cost was 95€ including labor, which was much more reasonable than a complete switch replacement. Before suggesting more specific solutions, could you share: Have you noticed any correlation between the erratic behavior and weather conditions? Does the issue occur more frequently when using specific light settings? Are you getting any specific error codes on the dashboard? Has there been any recent work done on your car lighting system? This information would help determine if your issue matches what I experienced with the wiring harness or if you might be dealing with a different automotive switch problem.

Had my last service at 175000 KM, and since then the electrical problem has gotten worse. The dashboard lights start flickering more frequently when its dark, especially when switching between high and low beams. The error codes point to a lighting system fault, and checking the fuse box showed all fuses are intact. The only recent work was installing new bulbs about 2 months ago, but the issue persists even with these new ones.

Thanks for providing those details. Just like on my XT5, that pattern of dashboard lights flickering specifically when switching between beams strongly suggests a wiring issue rather than a complete switch failure. Since you mentioned installing new bulbs recently, I recommend checking the connections at the headlight housings first. On these models, the wiring harness connections can work loose over time, especially after bulb replacements. The tail lights are usually unaffected when this happens. In my case, the dimmer switch appeared faulty because of a poor ground connection that developed over time. The symptoms got worse with mileage, just like yours. Before replacing any parts, have a technician test the ground connections and inspect the wiring harness near the automotive switch assembly. The error codes you mentioned are typical when there are intermittent connection issues. My repair started with diagnosing similar codes, but cleaning and securing the connections resolved both the codes and the flickering without needing new parts. Quick question: Does the flickering change intensity when you adjust the interior dimmer control? This could help pinpoint whether its a main switch issue or a ground connection problem.

I really appreciate the detailed feedback. The flickering actually does change when adjusting the interior dimmer, it gets worse when I dim the lights more. After reading about your experience, Im going to have my regular mechanic check those ground connections and wiring harness first before replacing the entire headlight switch assembly like the dealer suggested. The symptoms match exactly what you described, especially how the dashboard lights act up mainly when switching beams at night. It makes a lot more sense that this could be a wiring issue given the high mileage. If cleaning and securing the connections fixed it for you at a much lower cost, Id definitely prefer trying that route first. Will have it checked next week and inspect those headlight housing connections too since thats when the electrical problem started getting worse after the bulb change. Really hoping its just a loose ground connection rather than needing the whole dimmer switch replaced. Thanks for helping me potentially save on unnecessary parts replacement.