Wiring connectors

[jmartin]

Weatherpack is a common and lower-cost connector system. There are many Weatherpack kits (clones) available on Amazon for cheap, but they work well if you have the right crimper. Crimp tools range from $20 to hundreds - the better ones are ratcheting in order to "guarantee" a good crimp, but the cheap ones work too. Weatherpack terminals are open-barrel type, and you can also get uninsulated spade or ring type crimps that can be crimped with the same crimper.

For a bit higher quality, and more cost, look up the Deutch DT series. DT 3-pin. This 3-pin example is actually the standard J1939 connector that is found on many engines. These use a different pin style - the wire slides into the end then a crimper is used that impacts the barrel of the pin from several directions simultaneously. Many pin counts and styles are available.

Little DT kit: https://amzn.to/2CTXO7e

Large DT kit: https://amzn.to/2CUkK64
The above types are weatherproof, if you're making a harness that will be interior to the vehicle you can get other types made by TE etc that are not sealed.

Don't forget to grab the pin release tools for the different types of connectors.