Tracking down an electrical drain

[Dave G]

OK, full disclosure: the car in question is not a Festiva, but it could be, eh? :-)

The new battery in my daughter's Toyota seems to be being drained just a tiny bit when the car is off. Had the problem last winter and I got a new battery, which fixed it for the rest of the winter and through the summer. But now that it's cold again, the problem is back. It will get down to where it won't start, which is no fun at all. Anyway, I'm thinking the proper proceedure would be to pull fuses in turn and see which one makes the drain go away, then track down the problem in that circuit. My question is how do I measure the current flow during this test? All I've got is a standard multi-tester - can it be done with that, or do I need one of those clamp-on things?

[stefan]

You should be able to do it with your tester if it has an amps setting. You might have to switch around the positive lead to a different terminal on the meter. Then you put the meter in series with the battery. (In-between the positive cable and the positive terminal on the battery)

[lasvegascop]

Yeah, make sure the engine is not running!! hahahaha You will burn up your tester and alternator....but yes, put in in series and see how much is being used? Do you have an aftermarket radio installed?????

[mechanicaldj]

can be done cheaply with a 12v test light too

[jglutz]

Before I would start pulling fuses or tracing down circuits....I would completly disconnect any aftermarket devices added to the car.

Also...It would be best to just measure the volts to the battery while the car is at idle. Maybe the car is juts not replenishing the charge to the battery.

By today's standards.....most electrical devices are pretty robust and don't cuase leakage. Chaffing wires don't either...they result in blown fuses or fires.

If I were to pull fuses I would go after any related to the interior compartment lighting.

[Dave G]

Thanks, everybody! Follow-up: I did indeed test by pulling fuses, but in the process I talked myself into believing that the problem was a bad starter and/or solenoid. I'm thinking burnt contacts in the solenoid which made it fail only intermittently. So I replaced the starter/solenoid unit with a rebuilt one. Seems to have worked, as she hasn't had the problem since then :-)

[ndice87]

Columbus, right on. the best way is to take a 12v test light or 12v bulb and connect it to the positive battery terminal. Roll down the window of the vehicle and turn the car off. wait aprox one minute to time out any relays. then you want to remove the positive cable from the terminal with the light still in between. if the light is on this verifys that you do have an electrical draw. then pull fuses untill the light goes out. now you know what electrical system to search. from there it should be very easy to find.