What does a digital voltmeter reading of 878 mV during cranking indicate?

A digital voltmeter reading of 878 mV during cranking indicates that there is insufficient voltage reaching the starter motor, which is typically expected to be much higher, around 10-12 volts or more under normal cranking conditions. If the voltage is low, it often suggests that there is high resistance somewhere within the circuit, which could be in the positive battery cable, connections, or other components in the path between the battery and the starter.

In this scenario, the reading of 878 mV points toward a significant electrical issue affecting the starter system. High resistance in the positive battery cable could prevent adequate current flow, resulting in the low voltage reading. A defective starter might also lead to a similar situation, but the reading itself is primarily indicative of the resistance problem within the circuit. The idea is that since the voltage is too low for the engine to start, tracing the issue back to the positive cable and its connections is a logical first step in diagnosing electrical problems, which solidifies why high resistance in the positive battery cable is the most fitting conclusion from this reading.