What is the reason for the sudden increase to 4000 RPM when using cruise control downhill?

[LukeDella]

The reason for the sudden increase to 4000 RPM when using cruise control downhill is that the car's engine speed braking system is in control. Introduction to Cruise Control System: The cruise control system, abbreviated as CCS, is also known as the cruise control device, speed control system, or autonomous driving system. The cruise control system is a system that uses electronic control technology to maintain the car's automatic constant speed. Function of Cruise Control System: The main function is to lock the vehicle's speed according to the driver's needs, allowing the car to maintain a fixed speed without stepping on the accelerator pedal. When driving on highways, the driver can effectively reduce physical fatigue, and the car's constant speed can also save fuel consumption.