Does my Saturn heal itself overnight?

Three weeks ago, on my 2000 Saturn wagon, ‘check engine’ came on while driving & the transmission went wacky - shifting through low gears really roughly. After sittiing overnight, it was fine the next morning.

Two days ago, after picking up groceries, Saturn wouldn’t start, just wouldn’t fire. After a call to AAA, I tried again, it started, ‘check engine’ came on, drove home, and after sitting overnight, it drives great.

What’s the story here? I had it scanned, but there was nothing in the computer memory about any problems, and with ‘check engine’ not on, nothing to find out. I am mystified.

Have an auto-electric shop test your alternator for a weak diode. A failing diode will cause an AC ripple in the cars electrical system and some very weird things can happen…