F Type Random Light Activation Points to Faulty Switch

As an owner of a 2018 F Pace with some experience in car electrical systems, I encountered a very similar issue with the automotive switch system last year. The symptoms were nearly identical, unusual light activation and warning codes related to the lighting circuit. After diagnosis, the workshop found that the main car switch wiring harness had a damaged connection near the dimmer switch assembly. The cable insulation had worn through, causing intermittent shorts. They replaced the complete wiring harness and dimmer switch unit as a preventive measure, which cost 95€ total including labor. The repair completely resolved the unusual activation issues and error codes. No problems since then with any car lighting functions, including the tail lights. The workshop mentioned this was a known weak point in some models from that production period. To better assist with your specific case, could you share: The exact error code showing up, Whether the issue occurs more frequently when using specific lighting functions, If you notice any correlation with weather conditions, Whether the car switch controls feel normal or unusual when operating them This information would help determine if your F Type is experiencing the same underlying issue as my F Pace did.

Last service was at 130000km, about 6 weeks ago. The dimmer switch problem has persisted despite the electrical system check during that service. The dashboard lights and error codes only appear during cold starts, suggesting a potential connection issue rather than a complete switch failure. The dealership previously suggested replacing the entire car lighting control module, but it seems excessive given the intermittent nature of the electrical problem. Makes sense about the wiring harness, will have it inspected for similar damage near the switch assembly. My car lighting issues match your description exactly, especially the unusual activation pattern. Wondering if there might be a recall or technical service bulletin about this car switch wiring issue for our model years. The error code is B13940. Happens mostly when using the auto light function, less frequent with manual controls. No clear weather correlation noticed yet.

Thanks for the additional details. The B13940 code and cold start symptoms match exactly what I experienced with my F Pace before the repair. The similarity extends to the auto light function being more problematic than manual operation, classic sign of a wiring harness issue near the headlight switch area. I ended up documenting the exact conditions when the faults occurred, which helped pinpoint the root cause. The workshop discovered the wiring problem by checking continuity in the fuse box connections first, then tracing the electrical problem through the harness to the switch assembly. If the dealership electrical system check didnt include a thorough inspection of the wiring harness connection points, they likely missed the real issue. Before replacing the entire lighting control module, definitely have them check: Wiring insulation condition around the automotive switch assembly, Connection integrity at the fuse box terminals, Ground points for the lighting circuit The repair cost me 95€, much less than a full module replacement. Given your description matches my experience so closely, pushing for a detailed harness inspection could save significant expense. For reference, my unusual activation issues completely stopped after the harness repair, confirming the wiring was indeed the culprit rather than the control module.

Thanks for the input. After reading through the responses, I feel more confident about tackling this electrical problem with my F Type. The insight about the wiring harness being the likely culprit rather than the car lighting control module is especially valuable. The workshop quoted 850€ for replacing the entire lighting module, but based on your successful repair experience with just the harness and dimmer switch for 95€, I will definitely request a thorough wiring inspection first. The fuse box connections and switch assembly wiring deserve a closer look before committing to more expensive repairs. Will schedule an appointment tomorrow specifically requesting them to check the wiring harness near the light switch assembly and all related ground points. The fact that my B13940 error code and cold start symptoms match your experience gives me hope for a simpler fix than initially suggested. Will update once the inspection is complete and they identify whether the wiring harness is causing my dashboard lights and auto lighting system to malfunction. Thanks again for helping narrow down the likely cause of these car lighting issues.