310T Truck and Coach Technician Certification Practice Exam

To assess the condition of the cranking motor circuit, comparing battery voltage to starter terminal voltage while cranking the engine is essential. This process allows technicians to determine whether the starter motor is receiving adequate voltage during operation. If the voltage at the starter terminal is significantly lower than the battery voltage while the engine is cranking, it indicates excessive voltage drops due to potential poor connections, corroded terminals, or insufficient cable gauge. This check provides direct insight into the electrical efficiency of the starting system and identifies specific areas that may require repair or maintenance.

Each of the other methods, while useful for different diagnostic purposes, does not directly assess voltage drops in the same way. For example, checking and cleaning all connections is a preventative measure, but it does not quantify the voltage drop. Measuring starter cable resistance with an ohmmeter assesses resistance but not performance under load. Checking voltage across the cables while the engine is running does not focus on the cranking motor circuit specifically; it is more relevant to overall electrical load tests while the engine is operational. Thus, comparing the voltage at the battery and the starter terminal during cranking provides the clearest indication of potential issues in the cranking motor circuit.