Which action is necessary to verify after servicing a neutral interlock system?

Verifying the functionality of the shift control panel lights is essential after servicing a neutral interlock system because these lights provide critical visual feedback about the system's operational status. The neutral interlock is designed to ensure that the vehicle can only be shifted from a neutral position to a drive position in a safe manner, preventing unintended movement of the vehicle.

By checking if the shift control panel lights are functional, you ensure that the interlock system is correctly signaling the driver whether it is safe to shift. Malfunctioning lights could indicate problems with the interlock system or related circuitry, which could lead to safety risks if the vehicle is not in the proper state for shifting gears. This step confirms that all safety indicators are working as intended, thus ensuring overall operational safety and vehicle reliability after the servicing is complete.