To keep things simple, we specified the two most popular styles of automotive solderless connectors in the automotive aftermarket: non-insulated and insulated closed-barrel terminals. While some technicians apply solder to the non-insulated variety as a sort of insurance policy, that's a subject beyond the scope of this article (see the soldering sidebar), and one that we may address in a future installment.

Instead of endorsing any one particular style, we present to you several for you to choose from. As you do, keep in mind the following: Those who create entire wiring harnesses on OEM-level machines for our industry use at least one of these methods and tools to successfully install wiring harnesses. If you follow their lead and invest the time and attention necessary to do any job correctly, you're likely to achieve similar success.

To Solder Or Not To Solder
If there's a single most contended subject in the crimping world, it's the solder debate. We'll let Wire 1's Ken Whitney land the first blow: "When using a quality tool and when done properly, a crimp is every bit as good as any soldered joint. The conductivity and strength are both great, and the crimped terminal is as strong as or stronger than the wire itself."

Then again, both American Autowire's Michael Manning and Haywire's Ken Logue endorse soldering the tip of a crimped terminal to ensure the integrity of the seal. While Painless Performance's Dennis Overholser agrees with that in theory, he noted that, in practice, the occasional electrician is more likely to overheat and damage the wire than create a good joint.

Affordable Street Rods' Rich Fox outright condemns the practice and offers examples of failed solder joints made by aftermarket vendors. In fact, governing bodies like the Federal Aviation Administration permit only crimped joints, for reasons such as Whitney noted: "They figure that you're more likely to create an effective crimped joint than a soldered joint."

Luckily, they all meet at middle ground, as summed up by Manning: "A mechanical bond, generally in the form of a crimp, is the basis of any effective terminal installation." For that reason we have concentrated specifically on how to affect a reliable crimp and left soldering for another day.