Wiring

[Anon]

Our team is a pretty new team, and we are planning to take part in Italy FSAE 2015. We need help regarding the electical part of the car, as in how do we start with the wiring process?

[TiJei]

Hi Anon,

first things first. A little introduction of yourself and your team would have been nice.

Anyway, this is how I would do it:

1st: note down every part of your electrical system (a wiring diagram of the motorcycle your engine comes from is a good start to look into)

2nd: note down for every part which connection it needs (pinouts and/or circuit diagrams for your components should be available)

3nd: grab a big sheet of paper and place your parts around the corners strategically

4th: draw the connections you need to get every component working on the paper (again the original wiring diagram is a valuable blueprint)

If you done it right you have now a wiring diagram of your car.

5th: go to your car or CAD-model and package all parts of your electrical system

6th: consider were to route the wires in the car and define some cable trays (keep in mind that package priority of wiring is quite low as there are now structural implications to them, therefore you need to be sure not to route your wires at locations were something more important will be)

7th: check for additional connections needed to separate your wiring loom if necessary and include every connector in your wiring diagram

8th: measure the length of every cable route within your car, either in CAD or on the real car

9th: make a simplified drawing of your wiring loom which includes every cable route, branches and again connectors; The results should somehow look like a subway plan (Avoid ring structures under all circumstances)

10th: transfer your wiring loom diagram in original scale to a big plank and use some nails or screws to form a kind of channel for every cable route

11th: throw in all the required wires and bundle them together somehow; leave some extra length on the wires for branches and connector assembly

12th: put your wiring loom to the car and check wire length position of branches and connectors especially for the ECU

13th: assemble the connectors and test your electrical system

14th: if everything works, finish the bundling of your wiring loom

Congratulations: your wiring loom is finished.

Some additional advice:

Do not solder if you can avoid it. Use proper automotive style crimp connectors instead.

Get high quality tooling to assemble and also disassemble your connectors. Many problems occur because of bad craftsmanship during connector assembly

Get some spare pins and housings from the connectors of choice. Some stock material comes very handy in case of repairs or quick test of some new components.

Make sure you have spares of your critical electrical components that will stop your car running in stock.

I think that's it.

Regards
Timo

[mech5496]

Excellent writeup Timo! I will also include a (rather useful) link we tend to pass along our wiring guys:

https://www.rbracing-rsr.com/wiring_ecu.html

[MCoach]

+1 to Harry's link as I was about to post the same thing and is exactly what I sent my team when asked about acceptable standards.

[Anon]

Hello,
Thank you Timos and Harry for the reply. The stepwise procedure is really helping our electrical team.

We are done with the designing of the electrical circuit on paper. Now could you suggest any CAD software for designing the core electrical wiring of the car? The SolidWorks model of the car is still in progress, and we want a software used for designing just the basic circuit of the car. It would be helpful if you could specify the name of the software your team/other teams use.

[Dylan Edmiston]

A commonly used program is Microsoft Visio to create 2D drawings (honestly, MS paint could work too). Excel can be used to create a list of pinouts. Of course you need to logically plan out that paths of the wiring since it does not get imported into a CAD model. Lengths can be specified in the drawing by taking measurements off of the car, but it may be best to build the harness on the car to get precise lengths as get further down the build of the harness.

[apalrd]

Now could you suggest any CAD software for designing the core electrical wiring of the car? The SolidWorks model of the car is still in progress, and we want a software used for designing just the basic circuit of the car. It would be helpful if you could specify the name of the software your team/other teams use.

We use a well designed spreadsheet to design the harness, CAD software is also used to determine lengths and routing of the harness.

We also use PCB schematic/board design software for designing PCBs, but we don't use a schematic design program for the harness.