I got a DMM and the fuse TAPs will be here today. After searching YouTube I can't find a decent video or explanation on how to run the wires into the cab to connect to the switch. From what I found on T4R it looks like I can:
- cut the switch contacts off the wires connecting the switch to the relay
- cut off the little nipple on the large firewall grommet and feed the wires through the firewall to the cab
- reconnect the switch contacts to the LED wires and connect the LED wires to the switch in the dash
I get the impression this is the cleanest way to wire anything from the engine bay to a switch in the cab, yes? Am I missing anything?
I am likely to add a number of lights in the future: roof light bar, bumper mounted driving lights, side and rear lights. If I knew exactly what I needed to run I'd run all the wires now since I'll be in there but I don't. Is there anything I can do or should do to prepare for this eventuality since I'll be going through from the engine bay to the cab anyway?
The two most common, and probably easiest access points into the cab from the engine bay are the two large grommets on both the passenger and driver side on the firewall.
Word of caution... be stupid careful when doing so. Be absolutely sure not to compromise the factory wiring so dont start jabbing sharp objects though it or try to run it too close to the factory bundles. Don't use a screw driver or ice pick... Get it started using a pull wire with a rounded head and tape the wires you want to pull to it. Its not fancy, but I use some scrap solid copper wire from a home remodel.
Tip: Depending on what you are feeding though, the size, type of insulation on the wire, or jacket material, you might feel a bunch of resistance... Just like anything else you might try to penetrate, you might need lube. Non conductive dielectric grease would be a good choice.
https://www.amazon.com/Permatex-22058-Dielectric-Tune-Up-Grease/dp/B000AL8VD2
Regarding future proofing, its completely up to you what you want to run... but at least you are thinking ahead now... but ill give you some examples as to how I did it. You can decide how "crazy OCD" you want to get.
I spent a good amount of time planning, I only want to do it once and do it right, and I dont like fussing with critical areas like that constantly adding and removing wires.
I basically planned out switches, blank future adds, medium power, and a 50a mains run for a DC sub-panel inside the car....
I made my own "concentric wire harness" and sized wires accordingly.
https://www.youtube.com/watch?v=GLjKQHMU57k
I used 18 awg for control and indicators wire (switches and LED)
I used 14 awg for medium power
I used 10 awg for my 50 amp mains run for my dc-sub panel
Realistically you can use anything from 16 to 24 awg for control, but 18-20 is a good place to be. I went with 18 for more mechanical reliability, and because its easier to crimp.
Then do a concentric wrap to turn it into one big wire harness... Not my work, but should look something like this.
If that's literally too much work, then find some "multi conductor cable" in 18 to 20 awg... STRANDED... dont use solid core cat5 or something like that.
The latter being perfectly acceptable and the easy choice, the difference being the other is completely custom and built to your own spec / needs.
If you want to have a clean finish... crimp your end connections where needed, and use some type of quick disconnect connector to make it serviceable... just like how the factory did it.
You can either crimp your own connectors like these:
Or buy something like this and make only straight butt connections... not as clean, but works just as well. Sometimes it adds bulk, which is why the first option is preferred and looks a bit more professional.
Many electronic shops sell something like this with the male and female end with maybe about 6-10 inches of wire total. Ready to cut and crimp.
I know this is a lot to take in... probably way more than you need, but its just an example so you can get some ideas for your own project.
