Any electrical circuit that is wired "hot at all times" has the potential to become a parasite to the battery. There are some wanted parasites on the vehicle that are necessary to have, and some that are not. We're going to find out how to "fingerprint" and track down the unwanted ones systematically.

A parasitic draw on the battery means that, while the key is in the off position, something is pulling amperage from the battery. Like a glass of water that is slowly sipped on, it will run dry. The symptoms of a parasitic draw, or the customer complaints, can vary depending on the situation. Not every vehicle with a parasitic draw will come towed in with a dead battery. In fact, some may not even require jump starting to bring them in. It just depends on how low the battery is allowed to get before the next start. Intermittent electrical issues like:

gauges sweeping or inoperative at start up;

memory seats, mirrors and column not self adjusting;

radio presets disappearing; and

rough engine idle and harsh transmission shifting after first start-up in the morning are all possible symptoms of a parasitic draw on the battery. Any of those issues, and more, may have "healed" themselves by the time the customer brings it to your shop to check them out.