Alternators are an essential part of a car. They produce electricity to power all electrical items in your car and, when necessary, charge your battery. There are various types of Bosch alternators, but they are simple to wire and usually have three connections: red (positive), black (negative) and yellow (voltage regulator). Bosch alternators are maintenance-free. You can expect a Bosch alternator to last over 120,000 miles before it needs replacing.
Disconnect the positive and negative cables from your battery with a wrench. There must be no electric current anywhere in the engine compartment.
Locate your Bosch alternator and find the three terminals to which the cables attach. Each terminal is labelled positive, negative (or ground) and IND.
Unscrew the tabs on the alternator so you can insert the cables. Don't unscrew too far otherwise they will fall off and get lost in the engine.
Locate the three cables that attach to your alternator. They will all be nearby: one will be red, another will be black, and a third, smaller cable will be yellow.
Attach the negative black cable to the negative terminal of your alternator. Insert the wire under the tab and tighten.
Attach the yellow cable to the terminal labelled "IND." Sometimes this is a push-in plug. This cable goes to your ignition system. Tighten the screw.
Attach the positive red cable to the positive terminal of your alternator. Insert the wire under the tab and tighten the connection.
Reconnect the positive and negative cables to the battery terminals.