What do starting system voltage drop tests primarily help locate?

Starting system voltage drop tests are primarily designed to identify areas of high resistance within the electrical circuit of the starting system. When a voltage drop test is conducted, the voltage is measured at various points in the circuit while the starter motor is engaged. If a significant voltage drop is observed at a connection or component, it indicates that there is excessive resistance present at that specific point. This high resistance can cause inadequate current flow to the starter motor, leading to poor starting performance or even a failure to start the engine.

In contrast, low resistance generally allows for proper functioning of circuits, shorts typically result in a sudden drop in voltage across the circuit without the expected increase in current, and open circuits denote a complete break in the pathway that disrupts current flow. Therefore, this testing method is essential for diagnosing starting system issues related to high resistance rather than the other conditions.