Before you can begin to diagnose vehicle electrical problems, you must first have an understanding of electrical fundamentals. Electrical principles, like voltage, amperage and resistance, can be described as cars passing along the roadway. Voltage would be the vehicles speed, amperage would be the number of vehicles on the road at the same time, and resistance would be the potholes in the roads surface.

In this article, well go over some of the fundamentals of vehicle electrical systems, and then answer some questions you may ask yourself when working on an electrical diagnostic dilemma. Many technicians in the industry will tell you that in order to succeed in servicing and diagnosing problems in vehicles, you had better have a firm grasp of electrical properties.

Basically, electricity is a supply of atoms with an excess number of electrons. The flow of electricity would then be the actual exchange of electrons from atom to atom (see Figure 1) Keeping with the cars-on-the-roadway analogy, well also discuss diodes, DC and AC current, and define the term short circuit in this article.

Diodes are one-way traffic cops. They only allow the electrons to flow in one direction, similar to a one way sign on the streets; they are the check valve in an electrical circuit. The two ends of a diode are called an anode (+) and a cathode (-). The cathode end of the diode has an extra amount o...

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