Why does the CD player stop working when starting the engine but the radio works ok?

The CD player may stop working when starting the engine due to a temporary drop in voltage from the vehicle's electrical system during engine cranking. This voltage dip can disrupt the CD player's operation, as it may require a stable power supply to function properly. In contrast, the radio might have a lower power draw or a built-in capacitor that allows it to continue working during brief voltage fluctuations. Additionally, some vehicles are designed to prioritize essential systems like the radio when the engine is started.