BMW 328i alternator producing excessive voltage due to broken ground wire on BMW 328i

Some BMW 328i owners report experiencing excessive voltage from the alternator due to a broken ground wire, which can lead to significant electrical issues. These problems arise because the ground cables are essential for connecting the alternator and starter to the vehicle's electrical system. While the vehicle may operate without the ground wire, a properly grounded connection is necessary to maintain zero voltage. Owners are advised to check for corrosion, broken, or loose wires, particularly across ground straps linking the engine to the chassis and firewall. Testing each ground connection is crucial, as some may function correctly when the engine is off but fail under load when the alternator is active. In models like the BMW E90 and M3, the presence of multiple ground wires adds complexity, and if any are compromised, the vehicle may fail to start due to reliance on these connections for critical components like the DME and fuel injector relay. It is recommended to establish a reliable ground connection to prevent further electrical system issues.