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How to Wire a Denso Alternator

by Stephen Benham

Denso make aftermarket car parts for many cars, ranging from air-conditioning components, alternators and fuel pumps to smaller items such as spark plugs and wiper blades. Denso's regular aftermarket alternators produce between 40 and 160 amperes, depending on the type, but they also produce vehicle specific alternators that can produce greater amperes. Alternator wiring varies on the type of Denso alternator fitted in your car, but it generally fall into two categories: three-terminal wiring or four-terminal wiring.

Preparation

Put on lightweight protective rubber gloves before wiring your Denso alternator. You may accidentally touch a battery terminal and you certainly will get your hands dirty if you don't wear them.

Locate the black and red battery cables attached to your car battery, as you must disconnect them before wiring your Denso alternator. Remove the black cable attached to the negative battery terminal using a wrench. The terminal is labeled "Neg" or "-". This isolates electricity from the car.

Remove the red cable attached to the positive battery terminal using a wrench. It's labeled "Pos" or "+". Move the two cables away from the battery terminals.

Look on the back of the Denso alternator to find if it has three or four terminals. Follow the Steps in Section 2 and Section 4 if it has three terminals or follow the Steps in Section 3 and Section 4 if it has four terminals.

Three-Terminal Wiring

Look at the terminals and labeling on the back of the Denso alternator. One has a large plastic socket labeled "B" or "Bat". The other two are smaller sockets and are labeled "Ig" and "S" or "SL".

Locate two thin wires near the Denso alternator. You will find they have plastic plugs on the end and are slightly different sizes. The opposite end of one wire goes to the ignition warning lights, while the other is a low voltage wire that goes to the fuse box. Each plug can only fit into the correct socket, so insert one of the plugs into one of the sockets. If it fits, simply push it in until it clicks. Insert the plug on the wire into the small socket.

Locate the thick red cable near the alternator. It has a heavy plastic plug on the end. The opposite end connects to the starter motor and battery. Insert the plug on the end of the cable into the large terminal socket labeled "B" or "Bat". Push it until it clicks firmly in place.

Four-Terminal Wiring

Look at the terminals and labeling on the back of the Denso alternator. One has a large plastic socket labeled "B" or Bat". The other three are smaller sockets and are labeled "Ig", "PL" and "S" or "SL."

Locate three thin wires near the Denso alternator. You find they have plastic plugs on the end and are different sizes so you can't get the wiring wrong. The opposite end of one wire goes to the ignition warning lights, another is a permanent live low-ampere wire that goes to the battery, and the third is a low-voltage wire that goes to the fuse box. Each plug can only fit into the correct socket, so insert one of the plugs into one of the three sockets. If it fits, simply push it in until it clicks; if it doesn't, then try inserting it into one of the other two. It's a simple matter of elimination. Remember each wire can only fit into a certain socket.

Locate the thick red cable near the alternator. It has a heavy plastic plug on the end. The opposite end connects to the starter motor and battery. Insert the plug on the end of the cable into the large terminal socket labeled "B" or "Bat". Push it until it clicks firmly in place.

Completion

Check the wires and cables are securely connected. Gently push and pull each wired connection to check it doesn't come away from the socket.

Reconnect the red battery cable onto the positive battery terminal using a wrench.

Reconnect the black battery cable onto the negative battery terminal using a wrench. Make sure both cables are firmly attached.

Items you will need

About the Author

Stephen Benham has been writing since 1999. His current articles appear on various websites. Benham has worked as an insurance research writer for Axco Services, producing reports in many countries. He has been an underwriting member at Lloyd's of London and a director of three companies. Benham has a diploma in business studies from South Essex College, U.K.

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