Toyota Pick-ups, Land Cruiser, and 4 Runner 1997-00

Alternator Precautions


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Fig. Typical Toyota truck charging system circuit

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Fig. Exploded view of a typical Toyota truck alternator and related components

To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.

NEVER reverse the battery connections. Always check the battery polarity visually. This is to be done before any connections are made to ensure that all of the connections correspond to the battery ground polarity of the truck.
Booster batteries must be connected properly. Make sure the positive cable of the booster battery is connected to the positive terminal of the battery which is getting the boost.
Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction. This causes damage.
NEVER use a fast charger as a booster for starting the truck.
NEVER disconnect the voltage regulator while the engine is running.
Do NOT ground the alternator output terminal.
Do NOT operate the alternator on an open circuit with the field energized.
Do NOT attempt to polarize the alternator.
Disconnect the battery cables and remove the alternator before using an electric arc welder on the truck.
Protect the alternator from excessive moisture. If the engine is to be steam cleaned, cover or remove the alternator.