Hi Nutter.
Have a look at this post to help you out which fuse does what.
http://www.madabout-kitcars.com/foru...highlight=fuse
When Marlin supplied the loom, they included a little diagram with wire colour codes and where they are on the car. It's in electronic format on there CD I think. Also has a word document with it all in writing. Can post it on to this forum but don't want to in case of copyright from Marlin.
I started off with the standard Marlin loom and expanded it. For example, Marlin only supplied one relay for the cooling fan. Build had to supply a flasher relay. They were the only 2 relays used. I expanded the relays for Cigar lighter, Front/rear fogs and horn. And used another fuse box.
Also used a standard Rover fuse box for the engine and other bits as Marlin recommended for the rear of the car. So 3 fuse boxes altogether.
Now when design yours, you need to concider are you using donor fuse boxes (Rover for example), kit fuse box etc or a mixture.
Also make as easy as possible for builder with connectors on the end. So just plug and play. Then just say to builder, "here's loom", you need x.y.z fusebox and works with this engine. If that makes sense.