Which of the following is NOT a switch located in the cockpit maintenance panel?

The APU Start Switch is not located in the cockpit maintenance panel; it is part of the aircraft's normal operating controls, specifically for starting the Auxiliary Power Unit. The cockpit maintenance panel generally includes switches that facilitate maintenance checks and servicing while the aircraft is stationary and on the ground.

In contrast, the Ground Service Switch is used to connect ground power and manage certain ground operations, while the Avionics Warm-Up Switches are employed to prepare avionics systems before flight. Additionally, the Cockpit Light Switch allows crew members to control lighting for operational visibility during pre-flight checks and maintenance activities. All these switches are designed to support the maintenance and pre-flight activities of the aircraft, while the APU Start Switch is specifically for starting the APU, which directly powers systems instead of serving maintenance functions.