Advances in automotive electronics and an increasing number of the electronic modules in modern vehicles have required a simpler and less cumbersome method of module-to-mod-ule communication. In order to eliminate
the need for hard-wiring modules together which would require bulky, heavy, and expensive wiring looms, a lowspeed system of communication called LIN was envisioned by a few European automakers (BMW, AUDI, VW, Volvo and Mercedes-Benz). This laid the groundwork for and eventually became the system that nearly all automakers today use in one form or another.
Think of it as a simple Internet system which only certain modules of your vehicle are allowed to access and through which they can communicate with each other. They communicate anytime the ignition switch is on and the
car is running.
The LIN is considered a low-speed communication bus. It is simple and cheap to build and install, and the devices that use it are the ones that are not of the first order of importance for the engine and powertrain operations. Modules with critical functions, such as ignition, fuel and miss-fire detection, are connected via a high-speed bus, such as CAN (Controller Area Network). The items which do not need that fast rate of carrying orders, such as power windows, door-locks, blower motors, radios, etc., are assigned to the LIN communication network. Its speed can operate these devices rather ea
sily.
Newer and more complicated alternators that continuously change the voltage setting for a variety of operational modes, are good candidates for addition to the LIN system. So, gone are the warning lights or the PCM-activation of the
alternator. The alternator itself has become a module, and it is connected to the LIN bus of the vehicle.
The PCM, or any other module which controls the charging system, can have two-way communication with the alternator through a single wire—used
for activation, voltagesetting, fault-detection and any other bit of information. In case of a problem or a fault in the charging system, the LIN will carry the message to the module which is in control, which will turn the warning light on
to indicate a problem. All of this is done through bits of information that ride on the LIN bus.