My dad is restoring a 1969 MG Midget. The right turn signal stopped working. Using nothing more than a voltmeter, I found a disconnected wire and a short to the frame.
I replaced the entire length of wire that was failing with $3 worth of wire, solder, and heat shrink tubing.
The lesson here is repairability and simplicity.
We’re constantly lectured to be “environmentally aware” by companies that no longer ensure their products will last a lifetime. There is 0 reason a modern phone couldn’t be used for the rest of your life. My Brother printer is nearing 12 years and is still on the same damn print cartridge. My Neato robotics vacuum has had countless parts replaced and is about the same age.
If you truly want to be a good steward of the earth, stop demanding/consuming latest and greatest, endless product and UI refreshes, and instead demand 30+ years out of a product (with small repairs).
To do some wiring that'll be bulletproof and last:
1. get wiring rated for under-the-hood heat (the wiring sold at auto parts stores is no good for that)
2. get crimp-on connectors
3. cut the plastic off the crimp-ons
4. put heat shrink tubing on the wire, well away from the end
5. crimp the connector on
6. solder the crimp joint using a thermostat controlled soldering iron
7. move the heat shrink tubing over the joint, and heat it with a bic cigarette lighter to shrink it on
8. voila!
P.S. Crimped connections don't last. After about a year, they'll work loose a bit from vibration, and corrosion will creep in, and you'll get a loose connection that is very frustrating to find. Soldering it prevents that from happening.
Take a look at these:
https://www.amazon.com/Qibaok-Connectors-Insulated-Electrica...
Crimp a wire in it. Look at it from the connector side. You'll see the bare conductor inside the connector. That's where the moisture gets in. Heat shrink tubing won't shrink enough to cover that. Wicking solder into it will seal it against moisture and corrosion.
Never had trouble with the completed soldered/crimped connections for decades. I use them in my car. With crimp-only, it's only a matter of time till I get erratic connects. It's particularly irritating with the stereo, as the speakers go in and out or suffer the crackling with a loose connection.