Blade Fuse Rewire

Paint, body preparation and modification, interior work and electrical
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loungin112
Posts: 249
Joined: 05 Mar 2014 21:34
Location: Colorado

Blade Fuse Rewire

Post by loungin112 »

I completed a quick search on this topic and couldn't find the info I was looking for, so here is a new discussion post. (If you happen to find an existing topic, please post here and feel free to close this discussion.)

As I am rewiring a large portion of my car, I wanted to explore the idea of replacing my stock glass fuse box with a modern blade-fuse box. While I was at it, I figured I would mount it inside to clean up the engine bay a bit. But, as I began to further understand my existing fuse box, I realized there is not simply one power source coming into the stock fuse box....there are 3. The complication, as I see it, is the maze of crossing/sharing of grounds and positive leads that is created by the stock fuse box, which is not easily replicated by an updated blade-fuse box.

I have a wiring diagram, a testing light, and a decent understanding of the electrical working of our cars. (Even though, my fuse box is one of the weird ones with 4 individual wires coming out of the fuse box.)

So I ask, has anyone switched from the stock glass-fuse box to a modern blade-fuse box? If so, pictures and suggestions?

I'll put some photos up to enrich the discussion soon.
iceman510
Posts: 182
Joined: 27 Jul 2015 19:05
Location: Howell, MI

Re: Blade Fuse Rewire

Post by iceman510 »

This is doable as many have done it, but it certainly becomes an individualized installation. I have not done it, but have become quite familiar with the 510 wiring schematic over the last couple months as I repaired and rewrapped everything.

Of the 4 individual wires (not in the connectors) in the fuse box, only two of those are inputs. The large white is the main B+ input from the alternator and battery and feeds the BAT1 circuits. The Red with yellow is feed to the headlights (BAT2), so that could be worked out with a separate new headlight relay circuit which many do anyway. The large black/white (IGN) is output that feeds the ignition.

There are two other switched ignition inputs in the 6-pin connector that feed circuits for the IGN (small black/white) and ACC (blue/black). That should not be too difficult to get those routed to the appropriate circuits you want to run off those.

If you have the large blue wire coming out separately, that is basically an ACC switched power feed that you may not even need or use. It doesn't power anything in the stock 510 setup (can be used for AC) and is often wrapped and still under the fusebox unused.

Hope that helps.
iceman510
Posts: 182
Joined: 27 Jul 2015 19:05
Location: Howell, MI

Re: Blade Fuse Rewire

Post by iceman510 »

Diagram I made, with props to Kelvin as I consulted his 510 wiring diagram for color confirmations, etc. This specifically my 1973 MT, but other fuse boxes are similar.

I still don't fully understand how the headlight circuit works on the car (nothing is in it to test yet) but I am continuing to ruminate on it. If I have explained that part wrong, please someone enlighten me.

Fuse box diagram.PNG
Fuse box diagram.PNG (69.08 KiB) Viewed 197 times
loungin112
Posts: 249
Joined: 05 Mar 2014 21:34
Location: Colorado

Re: Blade Fuse Rewire

Post by loungin112 »

iceman510 wrote: 27 Apr 2021 11:09 Diagram I made, with props to Kelvin as I consulted his 510 wiring diagram for color confirmations, etc. This specifically my 1973 MT, but other fuse boxes are similar.

I still don't fully understand how the headlight circuit works on the car (nothing is in it to test yet) but I am continuing to ruminate on it. If I have explained that part wrong, please someone enlighten me.


Fuse box diagram.PNG
Thanks Iceman510.

Great diagram as well. I think I found 3 positive inputs, compared to your 4, so I'll have to take a look again.
That said, I'm considering a small blade fuse box for each of the 3 (or 4) inputs. The only possible trouble with that approach is if there are some cross-over dependency between the inputs. There shouldn't be, but I'll put my head into it next weekend. I plan on relocating all this new work onto a tray underneath the dash. I've got a plan for the tray, still trying to figure out a latch to keep it folded up underneath the dash though.

Your suggestions and thoughts are appreciated. Keep'em comin'.
iceman510
Posts: 182
Joined: 27 Jul 2015 19:05
Location: Howell, MI

Re: Blade Fuse Rewire

Post by iceman510 »

There is certainly possibility I am incorrect. I did this at the time of having none of the wiring harnesses or fusebox in the vehicle (done at the desk) as I was refurbishing all of them. I plan to connect up and verify this as everything is installed back into the shell.
demo243
Posts: 187
Joined: 19 Dec 2012 18:55
Location: Topsfield MA

Re: Blade Fuse Rewire

Post by demo243 »

It is definitely doable. The Z store has even redesigned plug and play fuse boxes for the Z. Unforunately I dont think there is anything like that for the 510... But, if you are rewiring a good portion of the car why not just start totally fresh and add/separate circuits? Especially if you planning on adding accessories - gauges, audio, engine swaps, etc.

Im sure it can be done using some simple fuse blocks and relays and building your own harness, especially if you have some experience, but what about using a pre-made option - ie American Autowire, Painless, etc. Sure they are "designed" around American vehicles, but can definitely be adapted to Datsuns.

I have rewired both my 510 and 620 using the American Autowire Highway 15 kit. It simplifies most things, by doing away with all the cross overs and shared power (I more then double the number of fuses!) and everything gets its own power. You can bump up to the Highway 22 if you want to add more fuses, or on my 510 I added an additional small fuse block - mostly for dash stuff - off one of the accessory fuses. It can be set up to use most if not all of the stock switches as well. I did use the American Autowire headlight switch, but still wired it to use the stock hi/low switch by adding relays for the headlights.

I had basically 0 wiring experience when I started the 510. I might go back someday and clean it up a little bit just to tiddy things up.
'71 4 Door - Street/AutoX/Track Day Romper - Carb'ed KA24DE
loungin112
Posts: 249
Joined: 05 Mar 2014 21:34
Location: Colorado

Re: Blade Fuse Rewire

Post by loungin112 »

iceman510 wrote: 04 May 2021 05:00 There is certainly possibility I am incorrect. I did this at the time of having none of the wiring harnesses or fusebox in the vehicle (done at the desk) as I was refurbishing all of them. I plan to connect up and verify this as everything is installed back into the shell.
Did some exploring with a test light yesterday, and here is what I came up with:

Constant: White (W)
Accessory: White (W) & Blue/Black (L/B)
On: White (W) & Blue/Black (L/B) & Black/White (B/W)

I think I will set up 3 Zones, 1 for each of the individual functions.

My concern: will all functions be maintained without doing some sort of leap-frogging between the different Zones? Do I need to use a pair of relays so the boxes can cooperate with each other?

I was thinking of using a larger box for the "On" function and a 6-blade box for both the ACC and On. There is room on my tray (see General Info - What did you do on your 510 today) for three such boxes.

Your critiques and suggestions are appreciated.
loungin112
Posts: 249
Joined: 05 Mar 2014 21:34
Location: Colorado

Re: Blade Fuse Rewire

Post by loungin112 »

demo243 wrote: 04 May 2021 10:53 It is definitely doable. The Z store has even redesigned plug and play fuse boxes for the Z. Unforunately I dont think there is anything like that for the 510... But, if you are rewiring a good portion of the car why not just start totally fresh and add/separate circuits? Especially if you planning on adding accessories - gauges, audio, engine swaps, etc.

Im sure it can be done using some simple fuse blocks and relays and building your own harness, especially if you have some experience, but what about using a pre-made option - ie American Autowire, Painless, etc. Sure they are "designed" around American vehicles, but can definitely be adapted to Datsuns.

I have rewired both my 510 and 620 using the American Autowire Highway 15 kit. It simplifies most things, by doing away with all the cross overs and shared power (I more then double the number of fuses!) and everything gets its own power. You can bump up to the Highway 22 if you want to add more fuses, or on my 510 I added an additional small fuse block - mostly for dash stuff - off one of the accessory fuses. It can be set up to use most if not all of the stock switches as well. I did use the American Autowire headlight switch, but still wired it to use the stock hi/low switch by adding relays for the headlights.

I had basically 0 wiring experience when I started the 510. I might go back someday and clean it up a little bit just to tiddy things up.
Trouble is, my harness is in pretty decent shape now! Cleaned it up quite a bit from the previous owner and now everything functions as it should. Plus, I've seen so many 510's languish because the owner decided to rip the harness out and start over...seems like a guaranteed way to keep mileage to a minimum. The additional fuse box could be a solution, one I've considered, so to not overload different power sources with multiple taps. I'm hoping to find a more permanent solution, simple as running a new wire, plugging in the appropriate fuse, which a blade fuse box would make possible.
demo243
Posts: 187
Joined: 19 Dec 2012 18:55
Location: Topsfield MA

Re: Blade Fuse Rewire

Post by demo243 »

loungin112 wrote: 09 May 2021 18:20
Trouble is, my harness is in pretty decent shape now! Cleaned it up quite a bit from the previous owner and now everything functions as it should. Plus, I've seen so many 510's languish because the owner decided to rip the harness out and start over...seems like a guaranteed way to keep mileage to a minimum. The additional fuse box could be a solution, one I've considered, so to not overload different power sources with multiple taps. I'm hoping to find a more permanent solution, simple as running a new wire, plugging in the appropriate fuse, which a blade fuse box would make possible.
I think many people over think it and never start the process of re-wiring... its a fairly "simple" job that just takes a good bit of time, but with a good diagram to understand how the 510 switches work it can be figured out. For me I like that it simplifies the wiring by getting rid of many of the splices, and adds in more fuses for individual items.

But --- if your harness is in good shape, I dont see why you couldn't just replicated the stock fuse box with a generic fuse box or two. You could probably piece together a pretty clean Bussman box, could potentially even pull some relays into it for an even cleaner look (or upgrading your headlight relays). The other option would be to simply use two fuse panels, one for ignition power and one for all time battery power. I think you need to tie a few circuits together, but shouldnt be too bad. With connectors from vintage connections you could have it plug directly into the stock harness plug.
'71 4 Door - Street/AutoX/Track Day Romper - Carb'ed KA24DE
loungin112
Posts: 249
Joined: 05 Mar 2014 21:34
Location: Colorado

Re: Blade Fuse Rewire

Post by loungin112 »

demo243 wrote: 10 May 2021 07:19
I think many people over think it and never start the process of re-wiring... its a fairly "simple" job that just takes a good bit of time, but with a good diagram to understand how the 510 switches work it can be figured out. For me I like that it simplifies the wiring by getting rid of many of the splices, and adds in more fuses for individual items.

But --- if your harness is in good shape, I dont see why you couldn't just replicated the stock fuse box with a generic fuse box or two. You could probably piece together a pretty clean Bussman box, could potentially even pull some relays into it for an even cleaner look (or upgrading your headlight relays). The other option would be to simply use two fuse panels, one for ignition power and one for all time battery power. I think you need to tie a few circuits together, but shouldnt be too bad. With connectors from vintage connections you could have it plug directly into the stock harness plug.
I'm going to keep thinking on how to maintain current functionality of the three ignition positions. I don't want to bugger it up.

While looking though, I came across this: https://www.amazon.com/Relay-Panel-Wiri ... 8149&psc=1

I'm wondering if this would perform the function of 3 Zones. If I'm understanding it correctly, I would still need 3 distinct fuse boxes, but this would should setup the On/Acc/Run functions. Right?

If this doesn't pan out, I'm going to go forward with moving the stock fuse box inside the cab and set it up for the conversion to something modern.....when I can figure out how to make it happen.
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