New front fuse/relay panel using busbar

[Pazuzu]

I'm working on a complete redesign of the front fuse/relay panel, trying to get away from high amp systems being fed through the existing ignition switch, getting away from the round Porsche relays which I am not a fan of, and simplifying the wiring to the fuses.

First note...I am not an engineer, nor an automotive designer, nor anyone who has any right doing something like this, so please, if I am doing something wrong please tell me! There might be secrets or basic design flaws to this which I do not know about and I would appreciate the people here who actually do know what they're doing to guide me.

I'm not the first by far to do a new system, nor the first by far to do the first busbar system. However, the front fuse panel is essentially 4 sections:

1) Closest to the front of the car is about 10 fuses that have a simple lead wire going in from a source, and load wires coming out to an assembly. In this case, it's all of the lighting. So, hot wire in from a switch, hot wire going out to lamps. So, lots of wires up top, lots of wires down below, each fuse is completely independent.

2) A few fuses that are powered from the "X" terminal of the ignition switch, which is hot in RUN and START. These are fuses were there is a main hot wire coming into the top, then hot wires going out the bottom to switches, which then send the load to assemblies. So, few wires up top, lots down below, with jumpers tying the fuses together.

3) A few fuses fed by the "15" terminal on the ignition switch, which is hot with ACC and RUN. Again, a main fat feed coming in, some jumpers tying the fuses together, then load wires coming out to feed switches.

4) Basically the same, but this cluster of fuses is fed directly from the battery, instead of the ignition switch, so they are ALWAYS hot.


What that means is, the scary mess of wires around the fuse panel can be split into 4 bundles based on how they are fed. This leads itself to running a busbar type power feed to them instead. 3 main feeds, and a set of individual fuses.

[Pazuzu]

Viola!



This is my new panel. I have 10 individual relays, 4 fuse "packages" for the 4 styles of power, a main busbar with positive and negative sides, then 2 massive 75A relays to switch the power to the fuse "bundles" from the ignition switch signal.

Instead of having all of the amps that feed a few fuses actually go through the ignition switch terminals, it will instead feed through those relays, with the switch only triggering it (sub-amp levels).
The fuse panels are 2 styles. The 3 of the left have been seen here before, they use a single feed in the center to power 6 fuses each. So, 3 panels for the 3 styles of power (always hot, hot on acc/run. hot on run/start). The 4th fuse panel on the right is a classic series of discrete fuses for the lighting.

Equipment:
4AWG cables coming in from the battery (two, red and black, positive and negative). They feed everything.

Busbar: Blue Sea 2722, 150A capable on each side, with a cover. Several mounting options.

Big Relays: Tyco 75A relay, V23232-D0001-X001. NO, SPST, 75A continuous.

Relays: Mix of Tyco SPST and SPDT as needed. The bases are shown, the relays aren't installed yet

Fuse panels: CE Auto Electric Supply, FPATC6 and FPATC9M panels. 40A each fuse, 150 A each panel, made in the USA.

8AWG wires feeding each big relay, 18AWG wire for the signal and ground of each relay, 14AWG supply and load for each relay.


10 relays, each has a separate color scheme. Fuel Pump, Power Windows, Cruise Control, Horns, Low Beams, High beams, Interior Accessories, Main Aircon, Evaporator fan, and a spare. 5 of them have power fed directly from the busbar as needed and are triggered from outside sources, while 5 of them get power from one of the bused fuse panels, then feed switch sources.

All said and done, there are about 50 wires coming IN, that need to be tied into this assembly.

[Pazuzu]

Yes, I have a diagram! The small numbered boxes along the edge are the 50ish wires that exist in the car chassis, that need to be tied into. I will probably just use marine heat shrink butt connectors, but I might add a few multi-pin snap connectors in the make the assembly removable. It seems like being able to disconnect the entire fuse/relay panel at once and diagnose things on the workbench would be really nice...


Oh, the mockup above, it's being made in 1:1 scale, so once I get everything happily run, it will transfer right over to a proper backing plate, which will be what goes in the car. Everything fits within a 6.5x21 inch panel.

Oh, I will have one spare fuse in each fuse panel for expansion, as well as the spare relay. Finally, the busbar has big 1/4 studs on the corners, which makes for easy locations to clip leads on the either pos or neg as needed, or to power something like a timing light.

Comments? Criticism? Suggestions?

[DRACO A5OG]

Wow, very nice work

Love to see it on the OEM panel or like OEM panel.

[Pazuzu]

Originally Posted by DRACO A5OG

Wow, very nice work

Love to see it on the OEM panel or like OEM panel.

So would I, there's no way this will fit. Although, it's not much larger that my existing setup, which is Fred Cooks fuse panel with the extra headlight relays hung on the end, plus an extra relay I mounted on the rear side (cockpit side). 6.5 inches tall isn't much larger than the existing panel.

I'm willing to give it more space in return for the ease of use and cleaner wiring.

[Pazuzu]

Also, notice that there are 27 fuses (24 being used), that's because I split a few things apart that didn't need to be ganged together like the factory did. I did share a few fuses, but those were either one big and one small load system, or two systems that rarely worked together, or a system that was transient, like the power windows.

I'm also running almost all LED lighting, so the 9 fuse panel will be populated with mostly 5AMP fuses, very low load.

[3rd_gear_Ted]

You can get fused buss bar assemblies to allow fusing before the relays

[jclporsche]

Nice project! I recently upgraded to Alan Louwerse CDD Autogear fuse block after tiring of ongoing lack of continuity on the 28 year old original fuse block. I like it well so far. But always looking for ways to improve her, as my daily driver.

[Glasgow 911SC]

There's also Classic Retrofits replacement panel.

911 Front Fuse Panel 1974 - 1989 - Classic Retrofit

[steely]

Awesome job Mike - I was going to comment on your first post about the ambitious-ness of the effort, but I am glad I didn't now that I see you've actually done stuff - kudos to you man. Glad you did a dwg, and it seems so well thought out. The proto-type looks great. (I have not studied it to see how you made the transition from old to new.)
Any thoughts as to the best or current planned location for the relays? What is the dwg app?

[Pazuzu]

I'll come back and answer some comments later when I have time, but I wanted to get this flowchart type diagram posted showing the layout in an easier to read manner...

[Carl_Boehme]

Mike;
A very well thought out and implemented project. Looking forward to seeing the final unit.
Carl

[James Brown]

a clear plastic watertight box would be great like a "Pelican" box

[Pazuzu]

Originally Posted by 3rd_gear_Ted

You can get fused buss bar assemblies to allow fusing before the relays

The fuse panels that I have are just like that, one main bus in split to 6 fuses. The difference is the ones I'm using are heavier than any others I've seen (40amp per circuit, 150amp per panel), which is much higher than what I've seen from Buss or Hella, for example.

My first design was simply replace the line of fuses with them, fed from the ignition switch and battery as stock, and only get rid of the mess of jumpers, but I realized that I wanted to take the load off of the ignition switch itself. Therefore, the extra 75A relays and main busbar.

Originally Posted by jclporsche

Nice project! I recently upgraded to Alan Louwerse CDD Autogear fuse block

Originally Posted by Glasgow 911SC

There's also Classic Retrofits replacement panel.

These, Fred Cook's design, even some of the other DIY setups all make for stronger fuses, but none of them clean up the assembly at all, nor do they strengthen/harden the harness behind the fuses. This setup *should* make the entire front electrical assembly much stronger, safer and cleaner.

Originally Posted by steely

Any thoughts as to the best or current planned location for the relays? What is the dwg app?

The relay bases are the long line across the upper left, there are 10 bases clicked together. So, when mounted, they will be front and center as viewed from the outside. Basic Bosch/Tyco cube relays.

Dwg program? Powerpoint! It takes FOREVER, is not at all the right way to do it, but after a few years of mucking around with it, I have a few tricks that let me build wiring diagrams with colored wires AND inset stripes!

For example, this is the main wiring harness that runs along the trunk of the car!

Originally Posted by James Brown

a clear plastic watertight box would be great like a "Pelican" box

If I was moving where the whole assembly was (a la SpyderMike), then yes, I would have made it a more square assembly and put it in a housing, but that just won't work where they exist now, it would be way too bulky. As it stands, the factory setup was FAR from waterproof, and had exposed hot wires everywhere, and didn't seem to cause issues, so this setup should be OK. There are still hot points exposed, so a cover will be needed, but at least the main busbar has a good cover built in, so you won't have a flat out 100+amp feed sitting exposed, waiting for something to bump into it...

[Pazuzu]

Well, time to revisit this. Seems that it took me 5 months to finally get the time to complete this.

So, after the 4 day holiday, putting in 8-10 solid hours per day under the bonnet, I have a new central nervous system in my p-car!

Initially equipment:


That is Fred Cook's fuse panel, with the extra headlight relays and an extra relay on the left side that kills the fuel pump remotely (I was having hot start issues with the Megasquirt...). The fuse panel, though build better than stock, was still having problems with meltdowns from various poor electrical loads. I wanted something more stable.


Step #1: Kill the patient



Here is what is behind the fuse panel, for anyone who is not brave enough to do something this stupid to their car

Panel removed, all incoming wires pushed out of the way.

Step #2: Clean up the crime scene



Factory harness sequestered based on my future connecting scheme. The bundle heading to the front of the car is the front lights (headlights, turn signals, etc), the condenser motor wiring and the wiper washer squirter motor.

[Pazuzu]

Step #3: Test fit the new brain and spinal cord



Here is a close up of the final wiring, with labels. I had test fit everything on wood, because it's super easy to make panel modifications to. For the final product, I transferred everything to a 1/4 inch thick UHMW poly sheet.

Step #4: Install the new nervous system



Here is the test fit of the panel. It's longer and deeper than factory, but that's the price you pay for glory Now, it doesn't exactly matter how big it is or how much stuff it blocks, because...it's 100% removable. Since I had to splice about 52 wires anyways, I had 2 options...butt connectors everywhere, or actual muti-pin connectors. It's the same work, the same number of fittings, but it makes everything removable.

Step #5: Slap the patient awake and test their cognitive skills...



Fully connected. Working on testing individual circuits, etc. 2 hours later, I drove the car out of the garage with a new brain.

I never took a final complete picture, so you'll have to wait on that.

[Pazuzu]

What's next:

1) The wiring is a mess. I can mostly shove it back into crevasses and pretend it's not there, but I pretty much expect to slowly update connectors and make it prettier.

2) Cover. it needs a cover. Probably just clear acrylic with some standoffs, I don't need an actual cover to surround it.

3) Fuse labels, etc. Probably printed and glued to the backside of the cover.

4) It also needs to be mounted. Right now it's just kinda tied off to the top of the front strut, I need to make some metal mounting bars to connect it to the inner frunk wall.

I bought a 12V power supply earlier this year, which proved to be invaluable. I could use it to power up small portions of the circuits one by one, instead of putting everything hot at once with a battery. It also has an amperage reading, so I could sort fuses with appropriate loads since my individual setup was different that stock (and I'm running almost 100% LED lighting).
https://www.amazon.com/gp/product/B00L2M2Y5O

As for the engine compartment...

When I installed the EFI, I rewired everything back there, I have all of the components (megasquirt, MSD, A/F sensor, etc) feed from a Painless relay block, it takes +12V always power right from the starter lead, +12V on run/start from the factory power lead (which powered fuse 22), and a relay to trigger several fuses on either always hot or triggered hot. So, it's kinda a complimentary system already to my new busbar stuff.

[Pazuzu]

What does this all mean now?

I now have a car with modern fuses. The ignition switch load is now only a relay trigger (1-3 amps tops?). There isn't 40+ amp loads travel back and forth through the car like before. The various systems are better balanced with regard to fusing. More relays with "modern" Tyco cube relays, which I can replace nearly anywhere if needed. I can kill, diagnose, test and bring back individual circuits or groups of circuits as needed. I can completely remove everything at once if needed (repairs, access to the gas tank, etc). Better connections to the battery (big fat modern wires, with big fact connectors, not ganged 10AWG wire trying to carry a massive load along 10 feet of wire).

I also built the system with spares. I have an extra fuse for each scenario (always hot, hot on start/run and hot on acc/run), and an extra relay which is already wired for power and ground, so I'd only need a simple trigger and load.


All in all, I like it!

[Pazuzu]

Oh! Also, every single wire is labeled on both sides of the connectors. I used my Dymo label printer connected to the computer to make nice clean 2-line labels with plenty of information, then used clear heat shrink to cover the labels up. So, i know exactly what each of those 52 wires is, and why it's there.

[somoney311]

Mike,

Excellent build! I am envious of your abilities to trudge through PowerPoint like a boss. I got the Classic Retrofits replacement panel for myself since I was also having issues with intermittent power output. It was a fantastic choice and now many of my systems run much better, it even brightened my headlights! I completely agree that the electrical wiring in these cars is something to be desired. One of my long term projects is to clean up all the wiring and upgrade them to better quality and consolidate/redistribute the load like you did. I just need to stop driving it everyday!

What model of Dymo printer do you have? That sounds like something I could use to catalog all the wires in an efficient manner.

Enjoy your work.