BMW 328i xDrive brake lamp malfunction related to rear unit control module on BMW 328i xDrive

Some BMW 328i xDrive owners report experiencing brake lamp malfunctions linked to the rear unit control module, which may indicate issues with the Footwell Module (FRM). These problems can manifest as the brake lamp lighting up during hard braking, suggesting a failure in the FRM. Additionally, owners have found that replacing rear lights, brake lights, and trunk lid lights, or even the entire module, may not resolve the issue. Some drivers encounter warning messages for a left brake light failure despite all lights functioning properly, which can potentially be remedied by cleaning corroded contacts or changing the bulb. Diagnosing the issue can involve testing for voltage at the wiring pin in the light housing harness while pressing the brake pedal, as zero volts on one side may indicate a problem. Common connector issues can lead to symptoms such as dead tail lights or malfunctioning brake lights. Checking for around 12 volts can help identify tail light problems, while a lack of voltage may necessitate inspecting wiring from the rear electronics module. In some instances, adjusting bulb contacts or ensuring bulbs are secure can alleviate issues, particularly in colder temperatures. These complexities underscore the need for careful diagnosis and resolution of brake lamp malfunctions in BMW 328i xDrive vehicles.