Current limiting
See VIDA Design and Function, Central electronic module (CEM).
This document describes the basic principles of the design and function of the generator (GEN), irrespective of the make.
The generator provides power consuming components with current while the engine is running and maintains battery charge. The generator (GEN) is mounted on the front edge of the engine.
The output of the generator (GEN) depends on engine speed. When the engine is idling, the generator (GEN) operates at approximately half of maximum output. When the engine is idling with many power consuming components engaged, the generator (GEN) may be unable to maintain full battery charge.
In cold conditions the capacity of the battery to receive charge is lower than at room temperature. This means that, when the engine is idling for a long period with a large number of power consuming components connected, the battery may discharge.
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.
First of all the generator (GEN) creates an alternating current (AC) which is converted to a direct current (DC) in the rectifier bridge.
The alternator has a built-in charge regulator (also known as the alternator control module (ACM)).
Note. Depending on the model year and type of engine management system, the charge regulator is connected to either the central electronic module (CEM) or the engine control module (ECM). It communicates via LIN communication. For information on connection, see the relevant wiring diagram.
The auxiliaries belt transfers power from the crankshaft pulley to the auxiliaries such as the power steering pump, air conditioning (A/C) compressor, and the generator. An automatic belt tensioner is used to adjust the belt tension. The belt is a Poly-v-belt.
The alternator with charge regulator is diagnosed via the central electronic module (CEM) provided the charge regulator is connected to the central electronic module (CEM).
If the charge regulator is connected to the engine control module (ECM), it is diagnosed by both the central electronic module (CEM) and the engine control module (ECM).
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).
Scheme 572
The left headlight control unit (LHCU) / right headlight control unit (RHCU) are located within the headlights.
The left headlight control unit (LHCU) / right headlight control unit (RHCU) handle the active regulation of the light beam. Active regulation means that the light beam is turned out to the left or right. The light beam is turned out at different amounts and different rates depending on vehicle speed and steering wheel angle.
Information is transferred between the left headlight control unit (LHCU), right headlight control unit (RHCU) and headlight control module (HCM) via LIN communication.
The lamp housing contains a sensor that indicates whether the light beam has been turned out to the right or left. The left headlight control unit (LHCU) and right headlight control unit (RHCU) send this information to the headlight control module (HCM).
If there is no communication with the headlight control module (HCM) or a fault arises in the left headlight control unit and/or the right headlight control unit (RHCU), active regulation ceases. If this is the case, the headlights are aimed straight ahead.
The left headlight control unit (LHCU) and right headlight control unit (RHCU) can be diagnosed.
The control module has a built-in diagnostic system, Volvo Diagnostic, which continuously monitors internal functions as well as input and output signals.
This function can be used to continuously read off the status of the control module's input and output signals.
For more information about parameters, see Vehicle communication information in Specifications, other.