Manufacturer ID as a key factor in generator replacement.
If the generator (also known as the alternator) is defective, replacement is often the only option today. But why does the warning message in the vehicle’s cockpit sometimes persist even after the generator has been replaced?
A common cause is the generator's manufacturer ID, which the regulator must use to communicate with the vehicle's engine management system.
Generator controllers with communication interfaces (LIN, BSS, and others) were introduced approximately 20 years ago. The MFR (multifunction controller – still used in some applications today), which was common before that, had preset values for control voltage, values for the ramp curve for LRS (Load Response Start) and LRD (Load Response Drive), and TK (temperature compensation). This reduced the control voltage depending on the installation environment of the battery with increasing temperature via preset curve values, or it was omitted entirely if the battery was installed in the trunk, for example. Due to the lack of an interface, these controllers could not be influenced from the outside.
Modern controllers, on the other hand, can be controlled by the engine management system. One of the pioneers of this technology was BMW with IGR (Intelligent Generator Regulation). This communicates with the generator controller using the older BSS (Bit Synchronous Interface) or the current standard for networking within the vehicle, LIN (Local Interconnect Network).
The flexible control of the generator regulator offers significant advantages in terms of fuel economy and lowering the engine power required by the generator during acceleration. This is achieved, for example, by reducing the control voltage so that the generator generates little or no electricity and therefore places only a low mechanical load on the engine. In moments of excess torque, e.g., when decelerating or braking completely, the voltage is increased in order to achieve as much battery charge as possible.
To use these functions, the generator controller must register with the engine management system for communication. There are IDs for this purpose, which vary depending on the generator manufacturer, generator size, etc. A replacement generator must use the appropriate ID to signal to the system that it is a product comparable to the original. There are many sources of error here. For example, if the engine management system requires an assumed ID of “123” to identify the generator, an assumed ID of “321” for the replacement generator would not allow communication. In this case, the replacement generator would run without functioning because it cannot be addressed.
The difference is not apparent from the outside. If you want to be on the safe side, only use replacement products from an original manufacturer such as SEG Automotive, as they usually have many years of experience in specifying spare parts. All other products may work, but there is no guarantee.
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SEG Automotive
Christoph Hoelzl
Press Officer / Pressesprecher
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press@seg-automotive.com