I've installed new car audio into my car. It works fine for a few months now. There is a USB port on the car audio for charging. Before actually using it, I wanted to test if it is safe enough and outputs about 5V.
So without giving a second thought, I grab my multimeter and set settings for direct voltage measurement. As I touched USB port ground and +5V pins, there was a pop in speakers and car audio shutted down, which pretty much indicated a short circuit.
After the incident I checked youtube video on how to measure USB port with multimeter. In the video, man used small metal pin between usb port pin and multimeter positive probe. (https://www.youtube.com/watch?v=xvSg1RiYDKQ)
So, as I understand, small metalic pin plays a role to reduce current? But how come measuring car battery or wall socket is fine by using multimeter probes, but not with USB port? Why short happened?
I have little knowledge about electronics and probably shouldn't stick multimeter probes in things, but curiosity took the best of me. Would appreciate any help or links to understand the issue.