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adding an aux fuse block

High Five H2

Well-Known Member
Messages
1,627
Location
West Texas
I was doing some research into wiring for my CB radio and i ran across some threads about auxiliary fuse blocks. I'm going to add more electrical accessories to my 3, so I figured I should just add what I need now. Any input? I'd like to add off road lights, front and rear, cb radio, maybe and air compressor, who knows what else.

Here's what I know so far: I need a fuse and a relay from the battery to the fuse block. I'm not sure where to wire to relay to that will turn on the fuse block. I'm not sure how many amps to the fuse block i need or how big of a fuse. I read up on a really handy thread on a FJ cruiser forum.

Input? While I'm at it, how about the alternator? should I do a bigger one? 2 of them? 6? a bunch of batteries?? (jokes)

edit - a winch, too, but something tells me that won't go through the aux fuse block.
 
Last edited:

alrock

El Diablo
Staff member
Messages
10,442
Location
Scottsdale
This fuse block from Amazon will probably be what you need: http://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B000THQ0CQ

You don't put a relay between the battery and the block. You'll put relays in line with the accessories that need them. You'll use a heavy gauge wire from the battery to the fuse block, and a heavy one from a ground to the block. Each accessory circuit will have its own fuse, and if necessary, its own relay.
 

High Five H2

Well-Known Member
Messages
1,627
Location
West Texas
the relay is what turns the accessory on and off with the vehicle, right? that way it won't drain the battery overnight?

that's the same one the guy with the FJ used. i'll put it on the list.
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
That one alrock posted is nice. I put one in a few months back with some new battery terminals. I put it just below the drivers side hood strut. I've got 3 relays next to it for the 3 sets of lights I'll be adding soon. It was a simple install and really keeps the wiring neat and orderly...
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
Ps.... The relay is controlled by the switch. 12v goes to the relay and closes the contacts allowing voltage straight from power source (battery) to go to the accessory. The relay can handle the current draw of certain accessories whereas the switch cannot. Essentially, the switch is turning the relay on or off (open or closed)...
 

High Five H2

Well-Known Member
Messages
1,627
Location
West Texas
so, as I understand it, the relay has 3 wires going to it - one to a power source, one to the accessory, and one that acts as a switch. Where do I plug in the switch wire to? after I figure that out I think I can get the rest.
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
Relay has 4 usually. 12v from battery across from wire to accessories
Wire from switch across from ground.

You're switch will have a 12v to it and a wire out to your relay. You flip the switch and 12v flows through the switch to the relay where it "picks up" the relay... There's contacts in the relay (12v from battery and wire out to acc.) that are now made allowing straight battery 12v to flow through to the accessory.
There basically 2 sources of 12v working here. 12v from switch to energize the relay and 12v from battery to feed the accessory...
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
If you do a search for aux lighting there's a thread I posted a while back about it. Someone (I think alrock) posted a diagram of how it works.
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
Yeah. That's a lot. I think I paid $30 for the blue sea fuse block. I got a couple cuts of wire, a waterproof inline fuse holder, a few different size maxi fuses (50a, 60a) for the block from amazon. You wanna make sure to put a main fuse in between the battery and the fuse block. I got a pack of 5 relays w/ sockets of eBay for cheap... I got some wire and wire loom from Walmart. And some other piddly stuff. I drilled a hole in the firewall and ran most of the wiring from the block/relays inside to the switches. Ran the wires from the block to the relays. All I need to do is run a ground and 12v to each of my 3 sets of lights (ground from block, 12v from relay) and wire up my switches when I get em. They will be lit up when the truck is on (switched acc 12v) and there's another light on them that lights up when the switch is on. I've gotta run that switched 12v to them and a ground. It can be a mind boggler at some points. Just try and plan out what you want to run off it so you can size wires and fuses accordingly...
 

06 H3

a.k.a. "The Jackal"
Messages
9,350
Location
Meridian, ID
I have a blue seas system in the garage waiting to be installed. It's a nice unit and would recommend it to anyone. My buddy has one on his jeep with no issues.
 

Chocflip201

In the Rocky Mountains
Messages
585
Location
Utah
I put mine here

gtqn.jpg

hdih.jpg
 

Chocflip201

In the Rocky Mountains
Messages
585
Location
Utah
Thanks. I was thinking about going on the firewall inside the cab where there is that blank space for the clutch pedal, but I also solder every single electrical joint that I make and I didn't want to be fighting trying to solder 24 wire ends underneath the dash. So I out it somewhere easily and quickly accessible.

I'm planning on dual batteries and I was going to put the 2nd battery over where the air intake box is and build a custom intake box, but I think I like it better with the two batteries turned sideways of the stock one and right next to each other better. And less work. Which means I'll have to find another place for my fuse block.
 
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