What is PWM and how is it used in automotive systems?

Pulse Width Modulation varies the duty cycle (on-time vs off-time ratio) of a square wave signal to control the average power delivered to a device. In automotive applications, PWM controls: Motor speed (fans, pumps, wipers), LED brightness (lights, displays), injector opening time, heater elements, and valve positions. PWM allows precise analog control using digital signals, reduces heat generation compared to resistive control, and is easily implemented by microcontrollers.