Toyota Problem Diagnosis

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The charging system converts mechanical energy into electrical energy when the engine is running. This energy is needed to operate the loads in the vehicle’s electrical system. When the engine is running, battery power energizes the charging system and engine power drives it. The charging system then generates electricity for the vehicle’s electrical systems. At low speeds with some electrical loads “on” (e.g., lights and window defogger), some battery current may still be needed. When the ignition switch is in the ON position, battery ..Mcurrent energizes the alternator. Alternator Mechanical energy is transferred from the engine to the alternator by a grooved drive belt on a pulley arrangement. Through electromagnetic induction, the alternator changes this mechanical energy into electrical energy. Voltage regulator Without a regulator, the alternator will always operate at its highest output. This may damage certain components and overcharge the battery. The regulator controls the alternator output to prevent overcharging or undercharging. High speed alternator Beginning with the 1983 Camry, a compact, high-speed alternator with a built-in IC regulator is used on Toyota vehicles. Corolla models with the 4A-C engine use a different alternator with an integral IC regulator. While engine speeds and electrical loads change, the alternator’s output must remain even - not too
much, nor too little. The regulator controls alternator output by increasing or decreasing the strength of the rotor’s magnetic field. It does so, by controlling the amount of current from the battery to the rotor’s field coil.

Diagnosis and testing - The charging system requires periodic inspection and service. Specific problem symptoms, their possible cause, and the service required are listed in the chart below. The service actions require a thorough visual inspection. Problems identified must be corrected before proceeding with electrical tests. These electrical tests include: an alternator output test, charging circuit voltage- drop tests, a voltage regulator (non-IC) test, charging circuit relay (lamp, ignition, engine) tests, and alternator bench tests. Precaution, problems and possible causes. download