How To Perform a Battery Current Draw And Locate Problems

Brought to you by 1AAuto.com, your source for quality replacement parts and the best service on the Internet.

Hi, everyone. I'm Don from 1AAuto.com. In this series of videos we're going to be focusing on vehicle diagnostics and maintenance tips. We hope that you find it helpful and when you need parts for your car or truck, think of 1AAuto.com. Thanks.

In this video, we're going to talk about checking for draw on your car. The reason why you'd do this is if your battery keeps going dead overnight or within a few days, it could mean that you've got a light that stays on or an after-market radio, or a glove box light that stays on when it shouldn't be on. Every car has its own preset amount of draw that it can have on it at any certain time. So just because the car's off and the key is out doesn't mean that the battery is not being used by a control module or something like that. It usually takes several several minutes for the car to "go to sleep", which means that the control modules settle down and they stop drawing. Well when they don't start drawing, that being a light or, say, a faulty control module that's when you get a draw and your battery's going to discharge prematurely.

What we are going to do now is walk you through the steps on how to do it. In order to do it you'll need to know where your battery is, a couple of vice grips and a multi-meter.

All right so we're going to do this on a 2006 Jeep Liberty. It's going to be the same operation for pretty much any car out there. You're just going to need to locate your battery and we're going to need to disconnect the positive terminal, before you do that be sure that you got a multi-meter handy. You're going to want to set it up like this. We're going to be switching over to the 10 amp setting. So I'm going to use a 10 millimeter socket wrench to remove this and I'm going to tuck this out of the way and I'm going to put a positive lead right here. Use a vice grip. Keep that out of the way. Use my other vice grip and put this on here.

You take your multimeter, switch it on and you're going to see your draw. So we've got 00.16 amps of draw at this moment. I want to show you what happens when we open up a door and the dome light comes on. So I've just switched on a dome light. You can see how thats had an impact on it. The draw's gone up to an amp, 1.34. See what happens when we got two dome lights on and it should've doubled. This is an unacceptable amount of draw. You don't want to have nearly two amps being drawn out your car when you're not in it.

Now let's take those- let's shut those lights back off and we'll watch it power down to where it's an acceptable amount. Like I said before, it's going to take a little time and you can see different modules that are starting to go to sleep and before long we'll let this sit for another few minutes and we'll see what it's at sleep mode amprage withdraw is. Now we wait a little while, we haven't touched anything, we haven't opened any doors to the start up any modules or awaken them up and you can see from here that you got 00.03 amps and that's really a good- that's an acceptable amount of draw. That's not going to draw too much from the battery while it's off, so that's good.

What we're going to do is we're going to show you, if you do have a draw that stays constant, that's too high, we're going to show you how to try and find it. So, now, let's diagnosis the draw. I set up a little bit of a simulation, I turned on a courtesy light in the back to simulate maybe a control module, a radio that's pulling a draw even when it's off, or a glove box lamp. So that's our draw right now. You can see that its 00.8 on the multi-meter which is a sizable amount of draw. That will kill your battery. So in order to do it to start, I'm going to leave this door open but I don't want the control modules to think it's open so I'm going to lock it and I'm going to make sure that everything else that could possibly be off is off. If the hood has a light underneath it, shut your hood. Just make sure everything- the doors are closed, the keys are out of the ignition.

So we see our draw, let's locate our fuse box and we're going to pull out each fuse until we see the multi-meter go back down to its acceptable level. Put it back in, pull it out, and put it back in. It's still at the high levels. There's nothing attached to these circuits so far that's pulling that draw. There's still nothing. Keep going, keep going. Pull this one. Yup. We can see from that, it's gone back to its correct level. Now you're going to want to reference your handbook, owner's manual or if it's been printed on the side of the panel on your fuse box, you can look at that and as it turns out it sure is the fuse for interior lights.

So we know and we found that draw. So it could be for you a radio like I said, any kind of module. This at least points you in the right direction. I'm going to wrap it up by shutting off my multi-meter, disconnecting leads and re-installing the battery.

We hope this video helps you out. Brought to you by www.1AAuto.com, your source for quality replacement parts and the best service on the Internet. Please feel free to call us toll-free, 888-844-3393. We're the company that's here for you on the Internet and in person.