What is a requirement for the function of the voltmeter during pre-trip inspection?

• A. It should show a negative charge
• B. It should stay lit even when the bus is off
• C. It should show the charging status of the alternator
• D. It should not work at all

Answer: (C)

The requirement for the function of the voltmeter during a pre-trip inspection is that it should show the charging status of the alternator. This is critical for ensuring that the electrical system of the bus is functioning properly. During the pre-trip inspection, the voltmeter provides the driver with real-time feedback on the voltage level produced by the alternator. A healthy alternator typically produces a voltage of around 12.5 to 14.5 volts when the engine is running, indicating that the battery is being charged effectively. If the voltmeter does not indicate normal voltage levels, it could suggest a problem with the alternator or the electrical system, which could lead to operational issues while on the road. Thus, the voltmeter is an essential tool for checking the overall health of the bus's electrical system before driving.