Wiring harness strategies.

alprada70 said:
I'm working on the electrical diagram and I haven't found 2 wires...
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Alvaro,

since you are doing '74, if you send me an autocad version of a file, i am happy to modify it for the earlier USA version + then we can look at other versions (which shouldn't be that much different). this is a really worthwhile endeavor for most coupe owners

scott
 
ScottAndrews said:
That's a great diagram!! Exactly what I was thinking of doing. The diagram gets much clearer when you remove all of the complex subassemblies and only look at connectors and terminals.

Now all we need is some way to impose dimensions, and identify wire bundles.

BTW, I noticed in the E9 diagram, there is really only one "splice"(in the headlamp circuit), but there are a number of small connectors that seem to join multiple wires. In the later ETM for the 635, BMW went to a slightly different convention separating splices and connectors, and providing detailed locations for each of them.
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One method to identify wiring bundles might be to attempt to replicate this type of diagram. Its a splice location diagram from the e28 electrical troubleshooting book, but I think this concept (if someone has the expertise to figure out how to implement it) could be used to detail the locations of each discrete wiring bundle:
 

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  • e28 wiring splice locations.pdf
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I think wire number 2 is the ground strap from the transmission housing to the body.
 
Ohmess said:
One method to identify wiring bundles might be to attempt to replicate this type of diagram. Its a splice location diagram from the e28 electrical troubleshooting book, but I think this concept (if someone has the expertise to figure out how to implement it) could be used to detail the locations of each discrete wiring bundle:
Click to expand...
Yes, this is where I am headed, but with much more detail. I want to have adiagram that itemizes the wires in each bundle, and then branches off to smaller bundles, eventually with some dimensions between bundle splits.

All of the wires in the harness have either multiple contact connectors (lights, switches, relays, etc, or they have individual spade contacts. In some cases these branch off to secondary harnesses, again, either via connectors or single wire contacts.

For example, the main front harness appears to connect either between components up front, or to the fuse box, to one of two connectors (37 and 40), or a small handful of discrete connections. There are some interior sub-harnesses, for example from the interior harness to the steering column.
 
I first wanted it to do myself also, but regarding time I went for Autosparks:
https://www.autosparks.co.uk/finder/car/bmw/3.0l+cs

Very satisfied about the result I must say. The picture shown of the fuel wiring harness is even a picture of my new one I dare to say. Before I brought mine they didn’t had one advertised like this.

Yes, it cost more money than making it yourself, but the harness is as far as what I checked color matching and very nicely made and saves you of course quit some time.
 
I've never spent so much time working on one of my reproductions. I worked about 120 hours on this project. I finished the electrical diagram and I'm working on an Excel document with all the information that is organized by wire number, cross section, colors and where it goes to where.

E9 1974 Electrical Diagram
303 wires, 123 accessories
3 wires missing: 102, 298, 299
5 wires with no information: 259, 260, 261, 262, 263.

What would be the best way to separate this information?
- 1 diagram only.
-by fuses, that would be 10 diagrams
-by wires in groups of 30, that would be 10 diagrams
 
rsporsche said:
my gut guess is the most helpful / interesting might be by fuse. we already have the single diagram as well as the group diagrams from BMW such as lighting, etc.
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I second that.
Easier to track down blown fuse issues
 
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When you ask me, the most helpful would be, separated by themes.
So as example, one for the wiper, one for the light, and so far.
If you searching an fault, it's more helpful to see only the wires from the affected system.

Breiti
 
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Breiti said:
When you ask me, the most helpful would be, separated by themes.
So as example, one for the wiper, one for the light, and so far.
If you searching an fault, it's more helpful to see only there wires from the affected system.

Breiti
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+1 - would be like this - which I find most helpful:
1730268692689.png



-Engine electrical
-Lighting
-Body electrical
-Wiper & Washer
-Signalling
 
alprada70 said:
I've never spent so much time working on one of my reproductions. I worked about 120 hours on this project. I finished the electrical diagram and I'm working on an Excel document with all the information that is organized by wire number, cross section, colors and where it goes to where.

E9 1974 Electrical Diagram
303 wires, 123 accessories
3 wires missing: 102, 298, 299
5 wires with no information: 259, 260, 261, 262, 263.

What would be the best way to separate this information?
- 1 diagram only.
-by fuses, that would be 10 diagrams
-by wires in groups of 30, that would be 10 diagrams
Click to expand...
I ended up with 305 wires.

Missing 163, 164, and 169

For the 3.0 CS, wires 259-263 are part of the electric window harness.

How these are arranged ina diagram depends on what ouare trying to accomplish with the diagram.

For troubleshooting, arranging by fuse is probably useful.

For re-creating a harness, arranging by bundle is essential. I like to think of the bundles as relating to different "geographic" parts of the car.
Each bundle branches at various points into smaller bundles, sometimes a bundle may be a single wire.

So following Ohmess's diagram above, we have a main bundle that goes to and across the front of the car, up at the radiator bulkhead. This originates at a couple of main connectors that lead inside the car (to the dash and steering column bundles), at the fuse box, and at various relays. So a useful diagram would show a bundle from some main component like a connector, with all of the wires listed for that bundle. At each place where a wire (or wires) enters or exits the bundle, the bundle name changes and the wire label gets re-defined with a different set of wires. Sort of as shown in the attached file.
 

Attachments

  • BMW E9 Harness.pdf
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Alvaro,

out of curiosity, have you set up layers based on each fuse? so that you can turn off layers to isolate the wiring of an individual fuse ...
 
rsporsche said:
Alvaro,

out of curiosity, have you set up layers based on each fuse? so that you can turn off layers to isolate the wiring of an individual fuse ...
Click to expand...
I think that's a great idea. Either layers, or just a set of seaprate diagrams each related to a specific fuse.

I still feel there are two different purposes for these diagrams. One is electrical troubleshooting, which the fuse specific diagrams would help with. The other is wire harness construction. These diagrams are not really well suited for that. I have been working on some slightly more "geographic" diagrams, were the harness bundes are clear. This combined with actual dimensions for the length between splits, and the length of split sections (a "split" is where a wire, or a smaller bunde of wires branches out from a larger bundle).

Here is a diagram I worked up in Eagle, which is a PCB tool. I did this because, as long as you keep the end points separate, each wire can be named (i.e. numbered), and the wires ("nets" in the tool) can be moved and re-arranged without losing their end point connections.

This diagram will not look as nice as the pictographic ones done by Alphrada because i have to keep each end point as a separate pin, so a device that has 2-3 wires connected to the same pin ends up in my diagram with three pins thatare connected internally. Rather than spend hours drawing each part as it is shown inthe original diagram, I just defined a set of black boxes with the appropriate number of pins. Hopefully, in the diagram below, some may appreciate the groupings of wires that will eventually become specific bundles in the harness.
 

Attachments

  • Screenshot 2024-11-15 at 10.36.34 PM.png
    Screenshot 2024-11-15 at 10.36.34 PM.png
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rsporsche said:
Alvaro,

out of curiosity, have you set up layers based on each fuse? so that you can turn off layers to isolate the wiring of an individual fuse ...
Click to expand...
I have each cable and accessory separately in a layer. There are about 430 layers. And I have an Excel list that I can sort by accessory, cable or color…
 
BMW3.0CSi said:
I first wanted it to do myself also, but regarding time I went for Autosparks:
https://www.autosparks.co.uk/finder/car/bmw/3.0l+cs

Very satisfied about the result I must say. The picture shown of the fuel wiring harness is even a picture of my new one I dare to say. Before I brought mine they didn’t had one advertised like this.

Yes, it cost more money than making it yourself, but the harness is as far as what I checked color matching and very nicely made and saves you of course quit some time.
Click to expand...
Hi,
Are you happy with Autospark wiring?
We are thinking of getting an order to them. Takes 8 weeks to make since they don’t have a LHD system available.
Thanks
Merdad
 
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