Wish you could have a quick-reference checklist for those perplexing problems that crop up from time to time? Engine won't start. Battery won't stay charged. Transmission slips. Clutch chatters.

U.S. auto safety regulators—who have been raked over the coals by Congress for failing to detect a broad pattern of ignition defects in General Motors Co. cars—are turning up the heat on Fiat Chrysler ...