how to properly wire along main harness?

Hi, I need to install an automatic daylight relay in my car. From looking into many engine compartments the eye always catches wires everywhere from DIYs. And it looks messy although it works. Many different colors and wires hanging everywhere. What is the best way to properly run new wires along an existing wire harness in such a way that the job looks tidy and professionally made? Is it a matter of choosing black wires only (so they will match the main harness), should you use cable ties, should you use Scotch 33 every 10 inches, should you fully wrap the entire wire for the entire stretch? Any tips? Photos would be nice :-) PS: I have realized that I will solder the wires to the existing harness as this is the preferred method discussed in this forum. Lucas

How you thought of using Split Wire Loom?  It comes in different diameters and colors.  You can use electric tape to seal the ends and every so many inches along it's travel and use tape or tie wraps ( zip ties ) to secure it to other harnesses, etc.Soldering is fun!

Split loom is the way to go if the OEM used split loom (and maybe even if they didn't). Exposed wires with no protection in the engine bay is not a good thing.Kevin Pierson

Hi, I didn't think of the split wire loom. The harness already has the loom in several places. So do you suggest: 1. Removing the existing loom (if present), fitting the extra wire(s) and putting the loom back on? 2. Fitting the new wire(s) and putting a new extra loom on top of the existing loom? Lucas

Run all new loom and keep it fastened up tight like the OEM loom. After 3 months you won't be able to tell what is factory and what is added. The 3 months gives the new loom time to get dirty like the OEM loom!Kevin Pierson

X 3 with Kregg and KP, cheapest source? Wreckers yard! Or one of my customers who's a sparks with the Docklands Light Railway.

Sources, Kramm in Denmark, they are an OEM supplier to GM etc. in Europe; Armour Auto in the UK, they supply most of Europe.

Wrecked VW's are another they have wonderful little seals at the ends.