Modernizing the Electrics

[Mister 4x4]

I don't know if this is going to be a great idea, or just a waste of money, but here's my plan.

As we all know, there are very few actual fuses and places to tap power from without cutting wires or overloading something for adding accessories or electrical upgrades. I have several electrical convenience items planned for mine, and honestly just don't want to mess with potentially chopping up the existing wiring harness.

Since I need both constant and keyed power sources, I've come up with this hair-brained idea to build a basic fuse block system to accommodate the things I'll be needing (first and foremost, the electric fuel pump hooked up to a keyed power source).

I think this illustration should be straight-forward enough. A circuit breaker straight off the battery (or maybe even the junction at the voltage regulator) running to a fuse block for constant powered items, and a key-powered relay to another fuse block for keyed accessories.



Painless Wiring has a keyed/relay-controlled panel, but it runs something like $90 just for 7 circuits. I found some Bussman 10-circuit fuse panels at Advance Auto Parts for $10 each (Bussmann P/N BP/15600-06-20 - http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_fuse-panel-for-atc-fuses--30-amps-bussmann_5171571-p?searchTerm=fuse+block&zoneAssigned=1), along with a heavy duty circuit breaker, some 12-gauge primary wire, and a 30-amp relay. The panel takes ATC (blade) fuses.

Now, I'm just trying to decide if I'm going to install it in some kind of a water-proof box under the hood (in the passenger side rear corner of the engine compartment), or try to find some place out of the way under the dash.

If anybody knowing a lot about our electrical systems see something wrong with this, please let me know and offer recommendations and/or other ideas. I'm wanting to install the following things: (Keyed-power) electric fuel pump, power windows, & back-up camera, along with (constant power) power locks/keyless entry, alarm system/LoJack, and 1 or 2 mid-range stereo amps.

 

[caspianwendell]

I would run the fuel pump through a relay after the switched fuse

 

[Mister 4x4]

I would run the fuel pump through a relay after the switched fuse

I thought about that also... but when I looked up the specs for the Holley Black fuel pump, it only has a 7.5 amp draw - which shouldn't tax the keyed fuse power much at all.

How would you wire up the fuel pump power with the added relay? Using keyed power? Or using the keyed fuse power to close the relay with power from another source (say, maybe a constant power fuse)? Either way seems like it's building redundancy into the circuit (either with the keyed power closing a relay already powered by keyed power, or by using the keyed fuse power to close the relay on another power source).

I welcome and appreciate the idea - I just need more information. ::thumb::

I've also thought about wiring in a switch on the fuel pump circuit as a cut-off switch for both safety & anti-theft properties - or maybe just let the LoJack handle that.

 

[Don C]

I would also run the fuel pump with a separate relay. You didn't say what size your circuit breaker is, for a 30 amp breaker I would use at least 10 gage wire, for a 50 amp breaker I would use 8 gage wire from the hot side of the starter solenoid to the breaker and to the fuse panels.

 

[Mister 4x4]

I would also run the fuel pump with a separate relay. You didn't say what size your circuit breaker is, for a 30 amp breaker I would use at least 10 gage wire, for a 50 amp breaker I would use 8 gage wire from the hot side of the starter solenoid to the breaker and to the fuse panels.

Good tip! I'll check - I'm pretty sure it's 30A (obviously, I will check on that for sure), since the fuse blocks are both rated for that.

Again, I'm not arguing at all, but can you elaborate on the fuel pump circuit having a separate relay? I've been looking closely at my other more modern vehicles, and it appears they have fuse panels (under hood) that are always hot, with the various major relays (fuel pump included) running keyed power to close the relay.

Is that a better way to do it? I'll draw up what I'm talking about later this evening - I'm WAY better at drawing than trying to explain.

BTW - Thanks for any and all the inputs to this. I'm just trying to make it safe and work right without having to hack-up anything that's not easily replaceable.

 

[caspianwendell]

The Idea of the modern relay system is to reduce the amount of circuits required to run all the accessories in the newer cars. the heavier load items are run through a constant power by means of a switched coil contact relay. This minimizes the amount of amperage that goes through the fuse panel. The things you are adding could be achieved by a power block, and inline fuses without chopping up the original wiring and could be easily removed, or updated at a later time. So to me having 2 fuse panels (in the case of our cars) is over kill. But, if you were completely rewiring the car, and have fuel injection, high amp stereo, LED lighting, and all the bells and whistles of new cars...then the idea of a non-switched sealed fuse panel-relay board under hood would be a great idea. The fuel pump relay will have a line (constant power), a load (to fuel pump) and a switched coil (to close the contacts). The back of relay will be marked with L1, L2, etc. so just follow the diagram when wiring it up...easy. That's just my opinion of coarse, and you know what they say about opinions...

 

[Mister 4x4]

LOL!! Ain't it the truth? But yeah - like I said, I'm happy for all opinions on this.

I think the reason the fuse blocks appeal so much to me is "centrally located." A lot of those devices with inline fuses can wind up having a fuse here, a couple fuses there, all in different locations depending on how the wiring of the devices comes out of the package.

I see where you're coming from, and I think I might just go ahead and incorporate a power block into the mix for the high amp devices, to keep the amperage through the fuse blocks low, as you mentioned.

Sound advice - I appreciate it!

 

[Mister 4x4]

OK, so I got my fuse box done and mounted. Everything's wired up, and works like a champ. But the cool thing is that it's modular, meaning that I can move it somewhere else or re-wire things if I don't like how they are. I took the 12V keyed 'On' wire I'd originally hooked up to the Duraspark module, and decided to power the relay with it, and put a 20A fuse in the block for the Duraspark module.

Constant 'On' fuse block on the left, keyed power relay in the middle, and keyed 'On' fuse block on the right. Main power running to the battery with a 30A circuit breaker and 10 gauge primary wire.

All closed up - everything fits and should be waterproof.

The place I originally wanted it was (will be) taken up by the hood hinge... dammit all. Oh well. I found a place on the front of the passenger side shock tower for now. I might just swap with the Duraspark module for aesthetic purposes... I'm not sure I like how it kinda dominates the engine bay. We'll see - not like I'm building a 100-point show car, after all.

I'm still debating on how to wire up the fuel pump with its own relay, but for now, it works just fine.