What is the function of the "High-Idle" switch in the Pumper units?

The function of the "High-Idle" switch in the pumper units is to adjust the idle speed for auxiliary equipment. This feature is crucial for ensuring that when auxiliary equipment such as pumps, lights, or other systems are operating, the engine maintains an appropriate speed to support their operation. By increasing the idle speed, sufficient power and hydraulic pressure can be provided to these systems, enhancing their performance without risking engine stalling or underperformance. This functionality allows firefighters to operate essential equipment effectively while managing engine efficiency and vehicle performance.

The other options do not accurately reflect the primary purpose of the high-idle switch—controlling engine speed for general performance or activating specific equipment like the winch or command light falls outside its dedicated use.