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1999 3.8 Parasitic Battery Draw

Old 07-04-2019, 01:18 AM
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BigBlockWagon
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Default 1999 3.8 Parasitic Battery Draw

This has been a problem since late last year when the battery suddenly went dead after sitting a few days. This is my wife's car and it's not driven all winter and I had to put a new battery in it last spring. The car is stock and alternator is only a couple years old. It has the Mach 460 factory system. I've narrowed it down to fuse #27 which is the radio which I assume triggers both of the amps. With the fuse pulled the draw is almost nil and is still holding at 12.8 after 3 days so far. Before this it would pull the battery down

I know I've read about these factory amps or relays causing a parasitic draw like this but what can be done to correct the problem? This has been very frustrating to say the least let alone she wants to drive her car

Any help would be a huge help!
Thanks, Ken

1999 35th Anniversary Edition Drop Top Mustang
3.8L V6, 5spd, 17" Bullit Wheels
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Old 07-04-2019, 08:53 AM
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Solara
 
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When you park it for the winter just remove the battery and put the battery inside somewhere that the cold cant get to it. Problem Solved. Any battery left sitting outside all winter, hooked up to a car that isnt being driven is gonna die.
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Old 07-04-2019, 11:14 AM
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BigBlockWagon
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Originally Posted by Solara View Post
When you park it for the winter just remove the battery and put the battery inside somewhere that the cold cant get to it. Problem Solved. Any battery left sitting outside all winter, hooked up to a car that isnt being driven is gonna die.
I should have specified better when posting that this happens all year and I can't even let it sit without running for 2 or 3 days or the battery voltage will continuously drop eventually to a no-start condition. I've done a parasitic draw test with my multimeter and found the draw is coming from fuse #27 which is the radio circuit but now the big question is why? I'm hoping someone has also had this problem and can suggest a fix.
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Old 07-04-2019, 03:01 PM
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Re install the fuse. Then Unhook the radio one component at a time until the draw disappears
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Old 07-05-2019, 10:53 AM
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Tnx Solara I'll give that a try to narrow the source of the problem down
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Old 07-05-2019, 11:00 AM
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I know that is not much help, but this is the only way I could approach it, cause I have never actually seen a new edge with the factory stereo that is drawing juice when off. If it were an aftermarket head unit I could guess that it had a wire crossed. Maybe there's a bypassed relay going to the amp? Could possibly be
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