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Old 07-17-14, 02:47 PM   #1
Michael
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Default 7 Amp Currnt Draw - Short Circuit Somewhere?

I am loosing 7 Amp of current constantly and is draining my battery. I must have a short somewhere and I cannot find it.

Most of the fuses are 10A and higher so I figure 7 Amp loss is not going to trip a fuse. I figure removing one fuse at a time to see if I can stop the current draw to isolate the area. I pulled every one of those fuses from under the hood and under the dashboard and still could identify the current lose source.

Anyone have any lead? Any help would be appreciated. Thanks in advance for you reply.

7 Amp loss was detected between positive terminal on the battery and positive cable after disconnecting the two.
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Old 07-17-14, 04:01 PM   #2
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I don't think it's a short otherwise it would blow fuses, imo. Is there something aftermarket fitted to your car, like an alarm etc, with a fuse somewhere else? Some alarms can draw a lot of power.
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Old 07-17-14, 05:03 PM   #3
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check your trunk wire harness on the driver's side hinge. constant open/close of the trunk usually tends to break those wires and cause shorts. a typical sign is also no reverse lights and/or intermittent brake lights.
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Old 07-18-14, 08:07 AM   #4
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Originally Posted by kevvo View Post
I don't think it's a short otherwise it would blow fuses, imo. Is there something aftermarket fitted to your car, like an alarm etc, with a fuse somewhere else? Some alarms can draw a lot of power.
If it is not a short, where is the current drain? With car ignition off, with key out, there is constant 7 Amp loss in electrical system. If I leave it alone, the battery is drained in one night.

Fuse will blow whenever the current is exceeding the fuse's current limit. For example, if the fuse is 10 Amp , the fuse will blow when there is higher than 10 Amp. Since most of fuses are 10 Amp and higher, no fuse will blow.

Nope, no aftermarket alarm is installed. I would always suspect what I've done to the car when electrical problem like this this occurs.

Last edited by Michael; 07-18-14 at 08:12 AM.
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Old 07-18-14, 08:56 AM   #5
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Originally Posted by timmy0tool View Post
check your trunk wire harness on the driver's side hinge. constant open/close of the trunk usually tends to break those wires and cause shorts. a typical sign is also no reverse lights and/or intermittent brake lights.
This is a good possibility. If there is 7 Amp short there, it should generate quite a bit of heat at the area of where short is. I reconnected the battery and first checked for reverse light. Both reverse lights came on. I then checked for any heat in the harness area and there is no heat being detected.
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Old 07-18-14, 10:03 AM   #6
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remove each fuse until the current drain stop. This way it will help you trace the issue
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Old 07-18-14, 10:11 AM   #7
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remove each fuse until the current drain stop. This way it will help you trace the issue
I've done exactly that. See posing #1, paragraph 2....
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Old 07-18-14, 11:13 AM   #8
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I've done exactly that. See posing #1, paragraph 2....
ok I guess I've skipped that part lol

Then I would try to unplug the alternator, maybe there's a diode that shorted in it causing the drain.
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Old 07-18-14, 05:10 PM   #9
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ok I guess I've skipped that part lol

Then I would try to unplug the alternator, maybe there's a diode that shorted in it causing the drain.
Nope, it is not the alternator. I have disconnected the alternator port and still drains 7 Amp.
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Old 07-19-14, 04:30 PM   #10
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looking at my batt terminal today I noticed that there's 2 sections on the positive post. I you could separate those 2 and isolate the drain on one of the 2.
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Old 07-19-14, 04:41 PM   #11
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Ok this is weird

according to this diagram (90-94 ls400) if you remove all fuses the circuit is open and should pull anything. either you miss one or the battery is the issue. (if I understand the schematic properly...)
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Old 07-19-14, 07:21 PM   #12
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Quote:
Originally Posted by lchouinard View Post
looking at my batt terminal today I noticed that there's 2 sections on the positive post. I you could separate those 2 and isolate the drain on one of the 2.
Thanks for your effort in trying to help. This topic is so tedious and there isn't much information available for me to work with. I am spending lot of time trying to gather a lead without much success.

You are absolutely correct that there are two sections on the positive post. I split the two and one does drain and the other does not. One is thicker one, I think goes directly into the starting motor and the other thinner one feeds into the fuse box under the hood. The thinner one is draining the current.

When I connect only the thick one only to positive post of battery, interior light does not come on nor starting motor turns when key is turned to start.

When I connect only the thin one to the positive post, all of interior light lit up. When I turn the key to start, just a click and starter does not turn.

If I connect both sections, I am able to start the car and all seems normal but I know there is a drain somewhere and fuse is not tripping.

??????
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Old 07-19-14, 07:36 PM   #13
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Quote:
Originally Posted by lchouinard View Post
Ok this is weird

according to this diagram (90-94 ls400) if you remove all fuses the circuit is open and should pull anything. either you miss one or the battery is the issue. (if I understand the schematic properly...)
I know battery is not the issue. I had a battery that was one month short of two years old I've been using that got drained completely when the car was not in use for about a week. It would not even take charge.

I took the battery back to where I purchased it and they give be a brand new one. Two year free replacement battery! The battery I have is brand new.

After the battery was installed, I've used the car few times. When I did not use the car for two days, the battery drained again. Not completely this time. I was able to charge to proper voltage. That is when I knew the electrical system is draining power.

I took the multimeter, disconnected the positive line and measured the current between the positive terminal and line. Sure enough there were about 6.8 Amp being measured.

The first thing I did was fuse test. I pulled one fuse at a time to measure the current loss and none of fuses didn't stop the current loss. I will do the fuse test again. Should relays be also tested? I did what I can the last time I did the fuse check.....
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Old 07-19-14, 07:56 PM   #14
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Quote:
Originally Posted by Michael View Post
The first thing I did was fuse test. I pulled one fuse at a time to measure the current loss and none of fuses didn't stop the current loss. I will do the fuse test again. Should relays be also tested? I did what I can the last time I did the fuse check.....
Every line has a fuse except the starter motor line, you know. You'd better to check more carefully.
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Old 07-19-14, 09:10 PM   #15
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Originally Posted by Yamae View Post
Every line has a fuse except the starter motor line, you know. You'd better to check more carefully.
Is there a fuse for the alternator? It is unlikely but how about line into the fuse box, both under the dashboard or under the hood?

7 Amp at 12 Volt is 84 Watts and lot of heat will be generated.....

If and only I can isolate to an area I can manage..... I can feel for heat to fine the short.
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