How Do You Connect an Alternator?

Connect an alternator by wiring the ground, output, sensing and indicator leads to their corresponding locations. Different automobile parts manufacturers have different color coding standards for their alternators' wires.

The first wire in the circuit of a typical alternator is the ground, although sometimes this connection is made through the alternator's case instead of through a separate wire connection. If a ground wire is exposed, connect it to a convenient spot on the chassis or engine block.

The second wire in a typical alternator is the output, which carries the charging current to the battery. Connect this wire directly to the battery, usually on the connection on the starter solenoid. Alternately, connect this to the battery's ammeter, if the vehicle has one.

The third alternator wire is the sensing wire that needs to be connected to the main battery supply circuit. This is either done directly or through a more complex series of connections. The sensing wire monitors system voltage and adjusts the charging rate to system load.

The fourth wire in a typical alternator is the indicator. The ignition switch delivers power to the indicator through the charge warning lamp when the vehicle is turned on but the engine is not running.