ABYC Diesel Practice Exam

Where should a technician begin diagnosing an engine that will not start after a power connection was added?

1. Fuel system connections

2. The choice of connection points for power and ground

3. Starter motor condition

4. Battery voltage

The correct answer is: The choice of connection points for power and ground

When diagnosing an engine that will not start after a power connection was added, it is crucial to begin with the choice of connection points for power and ground. This is because improper connections can lead to insufficient power reaching the engine or improper grounding, both of which can prevent the engine from starting. If the technician has recently added a power connection, it's possible that the chosen connection points may not provide the necessary voltage or current required for starting the engine. Additionally, if the ground connection is poor, it can lead to similar issues. Therefore, verifying that both the power and ground connections are correctly established is a critical first step in the diagnostic process, ensuring that the engine has the potential to start before investigating other components. Examining the fuel system connections, starter motor condition, or battery voltage may be relevant later in the process but would only yield meaningful insights if the power and ground connections are confirmed to be correct first. Ensuring these fundamental electrical connections are sound can save time and avoid unnecessary troubleshooting of components that might not be the root cause of the starting issue.