ABYC Diesel Practice Exam

If an engine turns over slower than usual but the battery is fine, what should be checked next?

1. Spark plug condition

2. Battery cable integrity

3. Engine compression

4. Starter relay function

The correct answer is: Battery cable integrity

When an engine is turning over slower than usual, it is essential to first confirm that the battery itself is functioning correctly. Assuming the battery is fine, the next logical step is to check the integrity of the battery cables. Battery cables are responsible for transferring electrical power from the battery to the starter motor and other components. If these cables are damaged, corroded, or loose, they can impede electrical flow, resulting in reduced cranking speed of the engine. This is particularly important because even a fully charged battery will not be able to deliver the necessary power to the starter if the cables are not in good condition. While the other options are also important checks in diagnosing starting issues, verifying the integrity of the battery cables should come immediately after confirming the battery's condition. Checking the spark plug condition typically relates to ignition problems rather than cranking issues, engine compression deals with the internal condition of the engine and its ability to produce power, and the starter relay function pertains to the electrical control side rather than the delivery of power through the cables themselves. Therefore, investigating the battery cable conditions is a critical next step in resolving the issue of a slow-turning engine.