Electrical Anomaly

We own a 1997 chevy suburban 2500 with 191,000 miles which has been experiencing electrical problems starting and after being started. On usually wet or humid days (usually mornings but also anytime during rainy weather) the electrical system is completely dead with no starting attempt or lights. After several rotations of the ignition key from on to off and on again the engine turns over normally and starts and then runs well. Lately this behavior has changed. Today the engine started immediately on the first attempt, warmed up fine, but stalled after backing up about 20 feet. The electrical system instantly went completely dead and the engine would not start. A rapid dull clicking sound was noticeable AFTER turning the key to OFF and removing it with the door OPEN. When the door was shut the clicking sound stopped. Also, turning on the headlight slowed the clicking sound although the lights did NOT light. Turning on the overhead reading spot lights stopped the clicking sound and those lights did light. After the engine stalls and after sitting for a few minutes the interior lights come on and the engine starts with a few attempts. The vehicle can be moved forward or backward about 20 feet or less but the engine dies again and this behavior is repeatable. Throughout this day the waiting period varied up to a few hours before the electrical system would respond for the engine to turn over.

Check for corroded battery terminals. I would also have your battery and alternator checked, as well as voltage drop along the cables.

Check for a defective or corroded battery ground cable. I have seen numerous defective ground cables cause "strange" and "intermittent" problems. It is usually overlooked as a cause, yet is one of the easiest and most inexpensive things to replace.