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Doing "Big 3" Upgrade, Need Help

4852 Views 2 Replies 2 Participants Last post by  BoarderM

I just bought a used 2008 Outback, no special package, just the normal options.

I have always wanted a quality sound system so I took the plunge.

Before I install my system, I wanted to do the "Big 3" upgrade.

I need some help/clarification specific to my year model Outback on which wires I will be changing out, and if you need explanation on the "Big 3" here is a link: How To: Big 3 Upgrade - Knowledge Base

First the wire from the alternator to the (+) battery:

OK, so you can see the wire coming from the alternator to the battery goes behind the yellow cap and then into the fuse box, and another wire going from the (+) terminal of the battery into the fuse box.

Here is a closer look:

The smaller wire is the battery to the fuse box and the larger is the alternator to the fuse box, and as you can see they are taped together as just before they enter the fuse box at the far right of the photo.

Next is the (-) terminal on the battery to the ground, which my (-) terminal from the battery attaches to the engine block here:

My questions are:

1. There is no wire from the alternator to the battery, there is a fuse box in the middle (or so it appears.) What should I do?

In other words, I was prepared to connect straight to the battery from the alternator, now I'm unsure.

2. If I connect the (-) terminal to the ground it uses now, would that be a perfectly fine ground? or, would it be better to ground to the chassis as I was originally intending and as the instructions for the Big 3 upgrade tell me to.

3. Can anyone tell me where the main engine to chassis ground is?


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· Registered
2 Posts
Discussion Starter · #2 ·
I've given it some thought, and,

My thought is that I can go Alternator -> Battery (+) and leave the Battery (+) -> Fusebox alone?

Does that sound right to anyone?

And, still wondering about the ground, I will think on it but still looking for some advice.

· Registered
2000 Outback Ltd.
205 Posts
Yeah, you can add a second postive cable from the alternator to the battery but you must add a fuse with it. The ground at the engine block is fine for the big 3. I wouldn't use the factory chassis ground for the big 3 though. I would use the front strut tower bolts. Don't know about your main engine to chassis ground but most chassis ground goes from the battery negative to the side sheet metal.
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