electrical and ignition Adding An Aux Fuse Box?

[tonybeemer]

No wires outside of wire harness.. Wiring up the m20 comp is easy .. Depends on what year comp you have it's only 5-6 wires you gotta tap into and the bitch should start .. Ill try and post some pics up for you

[brendang2000]

brendang, I had thought briefly about upgrading the fuse block to a newer style, but honestly didn't think it was worth the effort. Most of the original harness is actually in good shape, there are some problem areas, but they can be fixed.  If it were a complete disaster, I probably would have gone the GM/universal hotrod harness route.      What was involved with changing over to a newer ATC/ATO style fuse block? Is it just changing the terminal ends? 

 

Anyway just for clarification, I'm looking to add an additional fuse block under the dash, not replace the original fuse block.

 

Thanks

. Yea, I missed it that you just wanted to add an aux fuse block, sorry. I basically cut the wires off at every switch and soldered the new harness to them. All lights, gauges and electric fuel pump I terminated the new wire and attached, or installed Mollex connectors to make for easy removal. I also removed all original relays and installed Hella waterproof units, which I hid behind the headlights. It's a lot of work!

[brendang2000]

I saw painless has an aux fuse kit. Thought about making it myself. There's one strip for constant power, and one for switched. I'm not sure why there's a relay for the constant powered switch. Any ideas?

fe97dd437ce39768713048ad8caade54.jpeg

This kit sells for $175. I know I can build it for pennies on the dollar, but I need some help understand the purpose of the relays with respect to the constant power strip.

It looks to me like one relay feeds half the fuse block and the other relay feeds the other side, both being ignition power. A single relay would not be able to handle the currant of all those fuses. The "5" amp fuse is to protect the ignition power wire in case it shorts between the fuse block and relay. If the fuse block had battery power, it would most likely have a circuit breaker. Hope that made sense. I've used aux fuse blocks made by some of the big muscle car part suppliers and they worked well and were a lot cheaper than Painless. B Edited August 27, 2014 by brendang2000

[TurkisM2002]

Yeah I figured that. Their diagram doesn't fit the product description then. One of the fuse strips is supposed to be constant power, not switched. So why the relay? Anyway I found some mini atc fuse blocks that will do the job. The block is rated up to 100 amps. I was going to put an 80A relay between batt and the fuse block rather than have multiple smaller relays. However to provide enough power to the block I should run 6 or 8 gauge wire from batt to relay, relay to block right?. Do they make quick disconnect terminals large enough? I searched but the largest I found was 10 gauge.

This is my first foray into automotive wiring can ya tell:)

Thanks

[brendang2000]

If you want ignition power, then the relay is the way to go, but If you want constant power I would not use a relay but a circuit breaker. Something like this:

http://www.kayjayco.com/catPCCTBrakrs.htm

They are like a fuse but can be reset or are auto-reset. They also make circuit breakers that can handle the 100 amps, but they're a lot bigger. Wiring would be from the battery to circuit breaker to the fuse block. Keep the circuit breaker as close to the battery as possible. A fuseable link could be another method, but I never went that route. As far as what gauge to use, there are to many variables to say what you need. Check out this website,

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=5.211&voltage=12&phase=dc&noofconductor=1&distance=7&distanceunit=feet&amperes=30&x=79&y=7

You'll need to know how many amps the fuseblock will need and distance of the power wire. What ever gauge you use in the settings, make sure the voltage doesn't drop, if it does you need to use a larger gauge.

I never found high amp disconnects that were not huge. They were typically used for forklift batteries and the like. Hope this helps and if you need any ideas, let me know. B

Edited August 27, 2014 by brendang2000

[TurkisM2002]

Thanks B for the suggestions. Certainly will either use an inline fuse or circuit breaker, depending on what my power requirements are. 

 

Maybe someone can help me out here, but do I really need to run 4 or 6 awg wire to power a fuse block? The stock fuse panel in our 2002s are only powered by 12 ga, so 12 ga should be sufficient, no?  The power I'm planning on running is relatively short, maybe less than 3 feet, so voltage drop is minimal.

 

Found this wiring diagram at hotrod online. They only reference 12 gauge for their power needs.

 

[TurkisM2002]

Ah...disregard my post...there's no need for me to go heavy duty with this accessory panel. I don't have any serious power requirements, other than a stereo amp, but that would be tied directly to the batt....

[AustrianVespaGuy]

Here's some pictures of my additional fuse box (up in the nose) and relay box (black box on the fender wall) for my Megasquirt installation:

 

Oh, and the white box underneath the black fuse box is the +12V junction from the batter (located under the back seat).  And just for good measure since this stuff is all fresh on my mind, here are a few good places to look for/use existing wiring on squarie cars:

 

- Red/yellow 12V hot all the time from the cigarette lighter (c'mon, nobody really uses that thing!)

- Extra terminals on the back of fuses 3, 4, 11, and 12.

- If your rear defroster wires have decayed into nothingness, this also a good source (fuse 3) or a good free wire (blue/green) running between the front and back of the car.  I use this wire to power my EFI fuel pump.

- There's this weird 3 connector thing that I think was for a tii fuel pump that has hot in run/start (fused though) green/white wire in it:

 

Should help get you started, but PM if you'd like more details!

 

-Carl

Edited August 27, 2014 by AustrianVespaGuy

[TurkisM2002]

I'm looking for a nice clean place to mount an aux fuse panel and relay box. Is there room inside the car against the firewall under the dash? Or should I mount this in the engine bay somewhere ?

[Dave3x72tii]

I use the hella ato 4 or 6 position fuseboxes, and a single unloader relay underdash with e36 era fan type splices, one kl30(hot) and one kl15(switched with ignition) which allow for multiple uses and future expansion. I like the battery corner and under the hatshelf for location.

[TurkisM2002]

Dave do you have any pics of your setup? And which unloader relay are you using? Did one come on the 2002 or was that just later cars like E30 and e36.

Thanks

Edited September 8, 2014 by chrisracer79

[Dave3x72tii]

any 30a 4 prong relay works, powered up with key on. sorry no pics available

[02hobiedave]

I used this fuse box to add my Aux fuse box. It worked out good. http://fuzeblocks.com/ It has got the relay built in, it has six fuses. its small and very easy to use. I took out my old fuse box and stripped the add-on's from over the years and took the stress of the original electrical system. so my Radio, a/c aux fan, driving lights, aux gauge cluster and cigarette lighter. Hope that helps out.

Dave