Question about the measurement of wires

How did you manage to measure the wire and found out the measurements and draw it on your book?

Which wire are we supposed to use for this?

Are there any specific colours to use for the wires?eg. power red wire, ground,black. What’s the purpose of white wire?

Do you mean how long they are? One of the easiest ways is with simple lengths of string, have one end at the component, run it along where you want the wires(s) to go, to the ECU or PDM, and add a bit for trimming, or 15-20% if you'want to do a twist.

The wire(s) will normally be chosed by the gauge, which will depend on the current, the length, and how well it copes with the ambient and generated heat. Oh, and cost can be a big factor!

There doesn't seem to be much of a standard for the colours used, so usually you'de either use the vehicle's colours, those recommended by the ECU or PDM manufacturer on their schematics (wiring diagram) , or if you're able to buy a wiring loom with the controller, use it's colours.

Some manufacturers use(d) just black for ALL their wiring, with a number from 0-9 moulded into the plastic. It made chasing wiring faults a bloody nightmare, not just because the same colour was used, but because the same number would be used for multiple wires, as there were only 10 for the manufacturer to chose from, so they repeated.

You DO have to be careful with manufactures' OEM wiring, as sometimes they're live switched, sometimes earth switch, and most confusing I've seen both black or white used for grounds, and also white or red for 'power'.