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Discussion Starter #1
Hi Luders,

I'm back in the game. Just picked up a clean 1989 Si, I had a 90 S a few years back until the timing belt slipped.

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The issues i'm having is bad battery drain. If i let the car sit over night it won't have any juice left in the morning. I did some digging and found this "professional" wiring job under the hood. I was wondering if this could be the source of the bad battery draining? This looks like something was spliced in a few inches down the wire connecting to the positive battery terminal.

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It looks like the last owner upgraded all the ground wires. I originally thought that was what the problem was but i cut open a sketchy bundle of electrical tape and found this underneath.
 

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First fix that professional splice job.

Next, if you have an amplifier in your trunk, unhook it.

Then, if you still have a draw, pull out your trusty DMM, and set it to amps. With the battery at full charge, doors closed, everything off, and WITHOUT disconnecting the battery, put a small screw in the center of the NEG battery terminal, and connect the ground lead of your DMM. Now connect the positive lead to the NEG battery clamp. Your DMM should read 0.0 amps. now, remove the cable clamp from the battery terminal without disturbing the DMM test leads. Your meter should read 0.5 amps or less.

If you have more than 0.5 amp draw with everything off, remove the fuses from the underhood fuse box one at a time until your draw is 0.5 or lower. Which ever fuse reduces the draw is the circuit that you have a problem on.

If you do not have an ETM, let me know what fuse fixed the draw, and I will give you a new list of fuses to pull. If you do have an ETM, wedge the drivers door switch so the car thinks the door is closed, and remove one fuse at a time from the underdash fuse box, but only those fed by the suspect fuse under the hood. This will further pinpoint your draw.
 

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you need a multimeter to see what is draining all that amperage when the car is off.

see video for tutorial:
https://www.youtube.com/watch?v=zdIKNnwEjIs

just unhook fuses 1 by 1 until the drain goes away on the multimeter, then you'll know which circuit is the one draining.
 

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you need a multimeter to see what is draining all that amperage when the car is off.

see video for tutorial:
https://www.youtube.com/watch?v=zdIKNnwEjIs

just unhook fuses 1 by 1 until the drain goes away on the multimeter, then you'll know which circuit is the one draining.
exactly what I said. DMM=digital miltimeter. But the video is probably better than written instruction.
 

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^ to correct your statement though. it's not 0.5A that is normal, it's 0.05A or lower, mine is 0.042A in normal state
 

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Discussion Starter #7
Fixed it, turns out it was a garbage battery in addition to a garbage battery terminal. Thank you Luders....next project 6X9's in the rear deck
 
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