Ground detection
Ground detection To check for a ground you get a test light correct? Then you disconnect only the Ground from the battery, then you put one lead of the test light on the battery ground and the other end on a ground to the car (the one right next to the battery is the one i am going to use), then if the test light lights up, you have a ground. Is that correct? Then, you pull fuses one at a time till the light goes away, correct? the only fuse panels are by the driver door and under the hood drivers side? Then once the light goes away you find a diagram of the grounds for that piece of equipment? I havent ever done this before and want to make sure i am doing it correctly.
Also, just what ifs, what if the light doesnt go out after i pull the fuses in the fuse panels? is there any direct runs to the battery like maybe the alternator? What about the BCM, where is that actually located? So many questions I know. Just want to figure out this ground problem quickly. Thanks
Also, just what ifs, what if the light doesnt go out after i pull the fuses in the fuse panels? is there any direct runs to the battery like maybe the alternator? What about the BCM, where is that actually located? So many questions I know. Just want to figure out this ground problem quickly. Thanks
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Joined: Oct 2006
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From: Champaign/Chicagoland
Us a multimeter instead. What exactly is it you're trying to do or solve? Telling us the problem you are trying to solve would be much more helpful. Do you think something is shorted out/draining batt? It sounds like you're looking to check current draw, not voltage..
I am on battery 3 in 1 year, if the car is off for a prolong period then it wont crank up. I am trying to figure out why. I just disconnected the (-) from the battery and left the (+) connected and put the test light on the (-) of the battery and the ground right next to the battery and the light is lit. I removed all the fuses in the fuse panel inside the car and light stayed on, i am about to remove the rest of the fuses under the hood. If the light stays on, where else would i check?
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Joined: Jul 2007
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you need to dissconnect the negative side of the battery. Connect one side of your test light to the negative cable, and the other side to the negative post on the battery. That way you are completing the circuit. I dont know where else you would look but in the fuse boxes. If it is a direct voltage then you would have a major major problem, because the only placs I can think of is to the battery and to the starter. Those would cause major drains and probably a fire.
Joined: Nov 2003
Posts: 11,328
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From: Jacksonville, FL (originally from Toronto Canada)
fredmr39 is correct, you need to use a multimeter for this problem. I'm not one of those people who say a multimeter is always better than a test light - I use a test light whenever I want to check the existance of power or ground but don't care about the amount. In this case, you very much care about the amount.
There are several circuits in the car that draw power all the time and are necessary for proper function. None of them draw enough current to cause battery problems but they would certainly light up the test light and basically tell you nothing. You want to use a multimeter to determine how much current is flowing and find the circuit that is drawing excessive current when the car is off.
There are several circuits in the car that draw power all the time and are necessary for proper function. None of them draw enough current to cause battery problems but they would certainly light up the test light and basically tell you nothing. You want to use a multimeter to determine how much current is flowing and find the circuit that is drawing excessive current when the car is off.
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Joined: Nov 2003
Posts: 11,328
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From: Jacksonville, FL (originally from Toronto Canada)
You want to set the multimeter to amps. Disconnect either the positive or negative cable from the battery - it doesn't make much difference which one although the negative is used most often because there is less chance of causing a short if you slip. Assuming you use the negative side, connect the red lead of the meter to the the cable end and the black lead to the battery terminal. (Reverse these connections if you're working on the positive side.) This is so that any current will flow through the meter in the correct direction.
You can then start removing fuses until you pull one that causes a significant drop in the meter reading (say, 0.5 amps or more). That will be the circuit that is causing the drain.
You can then start removing fuses until you pull one that causes a significant drop in the meter reading (say, 0.5 amps or more). That will be the circuit that is causing the drain.
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Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
It sounds like you need to change the scale of your meter to read smaller amounts of current. Zero amps means no current is flowing. There should always be some current for such things as the radio memory, alarm system, keyless entry monitoring, etc. It should be less than one amp so check that your meter is set to read that range.
Do you have anything aftermarket installed on the electrical system? I would start by looking there.
Not blaming it just because it's aftermarket, but thats a good place to look first.
I do know that all cars see a <0.3 amp current draw. Thats normal.
0.4-0.6 ish is more than normal, but not severe. It would probably cause it to die if not cranked from time to time over a month or so.
0.7 or more would cause the battery to drain faily quickly.
Not blaming it just because it's aftermarket, but thats a good place to look first.
I do know that all cars see a <0.3 amp current draw. Thats normal.
0.4-0.6 ish is more than normal, but not severe. It would probably cause it to die if not cranked from time to time over a month or so.
0.7 or more would cause the battery to drain faily quickly.