Sheating a harness for a prototype vehicle

I want to get some inputs for building a harness for my vehicle which is basically a live prototype so to say, meaning I can't freeze the inputs for my I/O and neither can I freeze the actual hardware and even number of devices and communication protocols they will use.

I'm primarily not 100% sure on how to approach the harness arhitecture and also what to do with the sheating and design as I really need ok-ish mechanical and thermal protection but i need maximum modularity and serviceability.

You will want to create modular design with that I call "futurability" built in. This means you should plan for expansion, such as alternate ECUs, PDMs, and Dash / Loggers.

When designing the harnesses, plan on using sub-harnesses that will allow easy re-configuration of the I/O (for example, a sub-harness might have 4 analog voltage inputs and 2 analog temperature inputs, but you would use a 12-pin connector, so you could supply say 3 different power, and 3 different grounds. Initially you may need only a single 5V, and a signal ground and chassis ground.

The 'spare" power and grounds will be identified for their exact purpose in the future - like you want to use a pressure sensor that requires 12V, then you configure this connector for that. You might also want to run spare wires that don't connect to anything currently, this provides flexibility for splicing, or doubling current capacity not originally anticipated.

Good Luck.

David is right, sub-looms are a good way of working around these issues, bulkhead fittings are a handy way of joining them, especially if you use pin numbers much higher than initially felt to be needed.

It's not too clear just how much wiring is still to be developed, might be easier to run "cheap" wires, unsheathed except where heat wrap is required, through loose tiewraps using simple tiewrap mounts on the chassis/body. Then when you know what wiring you actually need, where you are going to place the components, how you want to run the wiring, etc, you can have a proper wiring harness made with a few spare wires for extras that may come up in the future.