I don't know of any courses, but watching all youtube videos by "Pine hollow auto diagnostics" will take you well through most parts; that guy specialises in vehicle electronic faults & explains everything he does.
"Basic vehicle electronics" like ignition modules? Or "infotainment systems" or like the LIN bus (or CAN bus controlling all the communications of lighting, sensors, HMI, etc? Which part of the car are you interested in?
Note that some require factory software and laptop (or custom computer). Some require factory diagnostic equipment available only to dealers (or authorized service centers).
You can check online courses on Coursera and Udemy for automotive electronics, or consider specialized training from SAE International or the Automotive Training Centre for in-depth knowledge.