mjwalfredo

So my positive battery terminal looks like a fire hazard with wires for my amp, aux backup light, upgraded headlight wiring harness, etc and I want to clean it up.

I thought I would do the big 3 upgrade at the same time. However, I am still a little unclear on which wires I need to upgrade.

Here is what I think I need to do:
Alternator to Battery Positive
Battery Negative to engine block (underneath the oil filter)
Battery Negative to body (short wire going to inner fender near battery negative)
Back of Engine block to body (on cowl)

I am just confused because that ends up being 4 wires instead of 3. Should I do all 4 anyway or am I not thinking about this correctly?

Also, can anyone suggest a good positive terminal that will cleanly accommodate all of those wires?

Thanks.

Elton

here's what i did get your self some marine style terminals... for the positive get a inline fuse holder like the ones for a amp... now the grounds if u look straight down on the frame there should be a bolt for a bracket on top sand the frame good and use that bolt... for the 2nd run it to the alternator bracket the fender ground can be upgraded if u choose to do so

Elton

also if theres a boat store pick up some battery lugs and solder then in with a torch

Greg_Canada

More grounds the better.
necessary are engine to battery, battery to body.

The one on the cowl is just a little guy... you can upgrade it if you like, but it's not nearly as important as the main ones.

mjwalfredo

Okay, I am still not quite clear. The bracket bolt on the top side of the frame, this is where I will attach a new ground run from the battery neg terminal? After looking yesterday, I did not see any ground from battery to frame. Just battery to engine block (is that the alternator bracket you mention?), and battery to fender.


Thanks for the replies.

jrock24

Can you please tell a Newb what the benefit of this is, and just to clarify the "Big 3" are the power and ground wires?

mjwalfredo

This has been answered so if you search for "big 3 upgrade" you can get the details. But basically the idea is to supplement the existing main 3 power and ground wires with larger wires. The benefit is that there is less resistance to the current flowing through the system and more juice can get to the electrical components.

I think it is debatable as to whether this mod is worth it. If you have a high output alternator and lots of lights / amps or other things that draw a lot of current then it seems to be worth it. If your truck is stock then it probably doesn't do much.

I've got a 125watt 4 channel amp and an aux backup light and 55/100 watt headlight bulbs. It seems like all the lights on my truck just aren't as bright as they originally were when I bought it so I am going to try this upgrade out.

mjwalfredo

From the12volt.com:

Definition: the "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis.˟ Some people replace the factory wiring; others add additional cables to the factory wiring.˟ This instruction is to add cables to existing OEM wiring.

That description confuses me when I think about the wires on my 4runner. 1 is clear. 2, I assume is the short wire from battery negative to the fender. 3, I thought was the small wire going to the cowl from the back of the engine.

To me it seems like the electrical system Toyota used on the 4runner doesn't quite match the description on the 12volt.com.

If anyone can explain the way the Toyota design relates to that description, that would help me understand what I am about to do much better.

Gerdo

The big 3 are big on 2nd gens because the wire they used was a little thin.
The big 3 are actually just the 3 grounds. Battery to body, battery to engine, body to frame. I will say that the battery to body wire is a little thin on our 3rd gens. That is one that should be upgraded.

mjwalfredo

Yeah, the battery neg. to body is wimpy.

I guess that I want to do this upgrade because I feel like the OEM connections look pretty weathered and I just feel like they could use some R&R..

So, the OEM wires are pretty decent on the 3rd Gen?

Gerdo

Except for that body wire. Think about how many electronics are grounded to the body. The body ground is only a 10awg wire, good for 30 amps.

Greg_Canada

Run 4 gauge everywhere.
Everyone hates a bad ground.

the stock alternator cable is decent, the engine ground is good, but the body ground is not. I still put 2x engine grounds in, just to be safe.

drpdmazda

Definition: the "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring.