System Overview

This document describes the basic principles of the design and function of the generator (GEN), irrespective of the make.

The alternator's function is, during driving, to provide power consumers with current and to keep the battery charged. The alternator is installed on the engine's leading edge and is driven from the crankshaft by a Poly-V-belt. Adjustment of the belt tension is achieved by the automatic belt tensioner.

First of all the generator (GEN) creates an alternating current (AC) which is converted to a direct current (DC) in the rectifier bridge.

At the trailing edge, the alternator has an integrated welded-on charging regulator. For 5-cylinder engine, the charging regulator is also called Alternator control module (ACM). It is possible to change the regulator. On the regulator, bolted against the rotor's slip rings, there are brushes (carbon). The brushes can be changed separate from the regulator.

The alternator's output depends on the engine's RPM. At idle the alternator only delivers approx. half of max. output. When driving at idle with many power users engaged, recharging of the battery may be affected negatively, that is, the battery is not charged. In cold weather, the battery's capacity to take a charge is not as good as it is at room temperature.

This means that idling the engine for a long time, with many power consumers engaged, the battery can be discharged.

If the generator charge is cut, the power consuming components of the vehicle are only supplied with energy from the battery, which means that the battery will eventually run flat.

The charge indicator lamp in the combined instrument panel is controlled by the driver information module (DIM) via signals from the controller area network (CAN).

The alternator and charge regulator are diagnosed by both the central electronic module (CEM) and the engine control module (ECM).