How to Read a Wiring Schematic for a Car
The wiring schematics for modern cars describe the wiring in a way to be understood by mechanics and electricians. These are not maps showing where wires or electronic components will be found. They use symbols to represent components, not pictures showing what those components look like. Tackling a wiring schematic the first time can be a challenge if you have no prior experience with electronics. However, with some patience, a bit of research and by following the steps below, anyone with a basic understanding of how electricity works can learn to read the wiring schematics for a car.
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Instructions
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1
Decide on one circuit within your car's wiring system to examine. Your car's schematics will show many circuits, including those for the alarm control, brakes, air conditioning, airbags, alternators, engine control chip, heater, horn, instrument panel, lighting and ignition. Focus on one circuit at a time.
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2
Locate the circuit system you have chosen in the wiring schematics.
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3
Make note of the colors used in the wiring schematic. For example, yellow is used for start terminals, and pink and green denote ignition terminals. Light blue wires are used for brake lights, and ground wires are usually black.
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4
Compare the wires described in the wiring schematic to the wires in your car.
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5
Trace the wires on your car, making note of each component they connect to.
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6
Compare the components in your car to the symbols on the wiring schematic, making notes as you proceed. For example, a wire is shown as a straight line. A fuse is a straight line inside a rectangle. A resister is a rectangle without a line inside. A motor is a circle with an "M" in the center.
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Read all of the notes associated with the circuit of your diagram. These will help you to make sense of the symbols and numbers and how they compare to the physical components on your car.
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8
Research any symbols on the wiring schematics you do not understand by talking to a mechanic or using online references. There are subtle differences between some symbols. Resistors, for example are marked with a jagged line while variable resistors are marked with the same line, with a small arrow on the bottom.
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9
Choose another circuit to examine in your wiring schematics. Now that you already know the meaning of the different symbols and letters for one circuit, the second circuit should be much easier to understand.
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