Description & Operation

WARNING: Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article.

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

The alternator generates an alternating current (AC) voltage in its windings as it is belt driven by engine. The integral rectifier converts this AC voltage to direct current (DC) voltage.

The voltage regulator, which is attached to alternator frame, controls alternator output to meet electrical system requirements. The regulator also controls charging system indicator light and charging signal (FR).

Fuse 2 supplies battery voltage to charging system indicator light. With engine not running and ignition switch in RUN, terminal L of alternator is grounded by voltage regulator and charging system indicator light. With engine running and alternator charging, voltage at terminal L rises and charging system indicator light will go out. The rise in voltage at terminal L also provides an engine running/charging system functioning signal to integrated control unit, EPS control unit, and ABS control unit. If alternator fails to charge, terminal L will remain below battery voltage and charging system indicator light will stay on.

The charging (FR) signal is supplied to Engine Control Module (ECM). The ECM detects whether or not alternator is charging and what charging load is by evaluating changes in charging signal. High charging demands place an increased load on engine. To maintain a more constant idle speed, ECM compensates for changing engine load by adjusting idle control.