GMC Yukon's Headlight Control System Fault Fix Guide

I experienced something very similar with my 2019 GMC Sierra Diesel. As someone with moderate car repair experience, I can tell you headlight beam adjustment issues can be really frustrating to diagnose. The symptoms were identical, inconsistent light intensity and the warning light constantly illuminating. After several attempts to reset the control module, I finally took it to a workshop. Their diagnostics revealed a defective servomotor in the headlight range control system. The beam adjustment mechanism was basically stuck, causing unusual height changes. The repair involved replacing the servomotor and recalibrating the headlight control module. Total cost was 1040 Euro, which included parts, labor, and system programming. The whole job took about 4 hours. To better assist with your specific case, could you share: Have you noticed any unusual noises when the headlights activate? Does the issue occur with both headlights or just one? Did the problem start suddenly or develop gradually? Have you had any recent electrical work done on the vehicle? These details would help determine if youre dealing with the same issue I encountered or if its something else in the headlight system.

Thanks for sharing your experience. My Yukon is at 145162 KM and showing similar symptoms. After reading your reply, I checked for noises during headlight activation and noticed a slight grinding sound from the left side. The auto-leveling system seems completely unresponsive when testing on uneven surfaces. The electrical connectors appear intact after visual inspection, but the beam adjustment continues to malfunction out of nowhere. Going to schedule a workshop visit to check the servomotor, sounds like that could be the culprit based on your experience. The grinding noise definitely wasnt there during my last service. Do you recall if your workshop had to order special parts or if these components are typically in stock?

Thanks for the update on your Yukon. That grinding noise from the left side is a telltale sign, exactly what I heard before my servomotor completely failed. The auto-leveling symptoms match perfectly with what I experienced. For my repair, the workshop had the basic electrical connectors in stock, but the control module and servomotor needed to be ordered. It took about 3 days for the parts to arrive. The lighting system components for these models are pretty specific, especially the range control hardware. Since youre hearing that grinding noise, I would suggest getting it checked soon. In my case, the longer I waited, the more strain it put on the entire auto-leveling mechanism. When they finally replaced mine, they found some minor damage to surrounding components from the faulty servomotor grinding against them. The shop should definitely run a full diagnostic on the control module while theyre at it. Sometimes these failures can cascade into other electrical issues if left unchecked. When they fixed mine, they also found some wear on nearby electrical connectors that needed attention.

Thanks everyone for the detailed feedback. After hearing about the similar servomotor issues, I went ahead and booked my Yukon in for next week. The grinding noise has actually gotten worse over the last few days, and the beam adjustment is now completely erratic. Called the workshop and they confirmed theyll need to order the headlight range control parts, but their supplier can get them within 48 hours. The electrical connectors they have in stock. Got quoted around 950 Euro for the complete fix including the light intensity calibration. Really glad I asked here before things got worse, definitely dont want to risk damage to other components from that grinding servomotor. Will update once the repair is done in case anyone else runs into similar headlight system problems on these models.