Amp draw test
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Amp draw test
If your battery is going dead and your not sure why, a amp draw test will help find it.
Start by removing the negative battery cable.
Disconnect the negative cable
Put the correct size bolt into the neg battery terminal(can remove the bolt from the cable, and install it in battery)......now get a jumper cable with alligator clips and attach to bolt on neg battery terminal and the other end to the neg battery cable.....should let this stay like this for about 10 minutes......this allows all modules in the vehicle to go to sleep....if you were to immediately attach the amp meter, you would get a false high reading due to the modules being awake and communicating with each other....
Now check your readings. You should have zero, or perhaps a few milliamp. If you have more than .05 amps or so you have something drawing power from your battery.
First, make sure all your doors are closed, and lights are off, trunk is closed, and if you have a under hood light the bulb is removed.
After that, start pulling fuses one at a time and recheck
Recheck the amps on each fuse. When amps drop you found a load.
In this example maxifuses were pulled, these in some cases split off to many other places. This will narrow down where to look. You can also pull fuses under the dash, remember, one at a time and retest.
When you narrow it down to the location of the draw, disconnect that item. In this case the relay of the power antenna was the cause of the amp draw.
Disconnect the item and retest. If your still at or very near zero, you have found the cause for your dead battery.
Start by removing the negative battery cable.
Disconnect the negative cable
Put the correct size bolt into the neg battery terminal(can remove the bolt from the cable, and install it in battery)......now get a jumper cable with alligator clips and attach to bolt on neg battery terminal and the other end to the neg battery cable.....should let this stay like this for about 10 minutes......this allows all modules in the vehicle to go to sleep....if you were to immediately attach the amp meter, you would get a false high reading due to the modules being awake and communicating with each other....
Now check your readings. You should have zero, or perhaps a few milliamp. If you have more than .05 amps or so you have something drawing power from your battery.
First, make sure all your doors are closed, and lights are off, trunk is closed, and if you have a under hood light the bulb is removed.
After that, start pulling fuses one at a time and recheck
Recheck the amps on each fuse. When amps drop you found a load.
In this example maxifuses were pulled, these in some cases split off to many other places. This will narrow down where to look. You can also pull fuses under the dash, remember, one at a time and retest.
When you narrow it down to the location of the draw, disconnect that item. In this case the relay of the power antenna was the cause of the amp draw.
Disconnect the item and retest. If your still at or very near zero, you have found the cause for your dead battery.
Last edited by jwfirebird; 01-21-2015 at 12:15 PM.
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