Handbook 652 Body Electrical Diagnosis Series-Parallel A true series-parallel circuit has a load in series connected to multiple loads in parallel. In this type of circuit, the load in series causes a voltage drop so the parallel loads receive less than full source voltage. Resistance To find the total resistance of a series-parallel circuit, add the resistance of the series part of the circuit to the resistance of the parallel part. In a sense, when the total resistance of the parallel part is determined, the entire parallel segment is treated as if it were a single series component. Why Does It Matter?
Calculating voltage, current, and resistance in a circuit is not essential for repairing automobiles. What is important is understanding the relationships between voltage, current, and resistance. You need to be able to predict what should happen and compare it to what is happening in a problem vehicle. The principle of voltage drop is by far the most useful concept available for making diagnosis quicker and easier. Later, as you become more familiar with electrical theory and concepts, you may have an opportunity to perform calculations like the ones we have discussed here. Technical Training 33