That trick about pulling a battery cable to check a charging system went out of favor at least 40 years ago. The voltage spike from the charging system as the connection is broken can destroy thousands of dollars' worth of computers. I've had an oscilloscope on an electrical system to demonstrate that to my students. When a battery cable is disconnected with the engine running, I've seen spikes in excess of 100 volts DC. That can fry lots of computer circuits on anything with solid state components, including an electronic voltage regulator.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!