Butt connectors are one of the most common types of wiring connector, and are designed to splice the ends of two wires together. These connectors feature a straight internal crimp splice and an outer sheath that shields the connection against grounding or short-circuiting. Some butt connectors even feature heat shrink, which can be used to seal the connection and prevent water or debris from corroding or shorting the connection. Butt connectors also require two crimps: one for each piece of wire being connected at either end. There are three sizes of butt connectors available for most automotive wiring repairs that are color-coded to correspond to a range of wire gauges, ensuring the tightest possible splice and the best conductivity.
Whether you’re adding auxiliary lighting, installing an aftermarket radio, repairing the factory wiring, or performing some other electrical work in your vehicle, at some point you will likely need to use crimp-style wiring connectors to ensure a secure connection. Crimping wiring connectors and performing basic wiring installation and repair is a simple, straightforward DIY task, but many people choose to leave these types of jobs to the professionals because it can be daunting the first time you work on your own wiring. We’ve prepared this instructional article to provide the necessary steps and information to help you feel more comfortable with basic wiring repairs and crimped wire terminal installation.
Types of Wiring Connectors
If this is the first time you’ve taken on wiring repairs, you may be unfamiliar with the wiring crimp connector options available for your project. There are a variety of connectors designed for specific purposes, including different connection types, splicing, and more. Below, we will describe each type of crimp connector and their intended purpose to help you better understand your options.
Butt Connectors
Blade / Spade Connectors
Blade or spade connectors, also called quick connectors, are designed to fit a variety of terminals you might find on original or aftermarket electrical equipment. These connectors can be either male or female, and feature a flat connection style in a variety of sizes. Female blade connections may be used to connect speaker wires to automotive speakers, or may be used on a variety of original and aftermarket switches. Quick connect-style blade connectors fit together to allow the circuit to be completed and disconnected as needed while preventing grounding or short-circuiting. Flag-type blade connectors that form a right angle for connections in tight spaces are also available.
Ring Terminal Connectors
Ring terminals are flat, round connectors with a hole in the center that are mostly used to form aftermarket ground connections. This can be useful when installing aftermarket stereo systems, including radios and amplifiers, or to ground auxiliary lighting assemblies to the frame. Ring terminals can be used with existing fasteners, or self-tapping screws may be used to ensure a complete ground connection and prevent the connection from loosening over time. There are a variety of ring terminals available, and different sizes may be necessary depending on the connectors or fasteners being used. Some even include heat shrink for use on the exterior or frame of the vehicle to provide a waterproof and corrosion-resistant connection.
Barrel / Bullet Terminal Connectors
Bullet or barrel terminals are another type of quick connector, and similar to blade connectors, are available in both male and female configurations. The extended, round connectors are designed to fit together to form a secure connection and are insulated against grounding once connected. These types of connections may be found in the stock wiring harness, and are also an excellent option for adding accessories that may need to be disconnected later. Female bullet connectors can also be used to form ground connections with the exposed threads of bolts similarly to a ring terminal, but without requiring a nut or other fastener to secure the connection.
How to Strip Wires
To properly crimp wiring connectors and ensure connection and continuity, it is necessary to strip the protective insulation from the end of the wire. Wire insulation prevents power from arcing, which can cause grounding and short-circuiting issues, and it is imperative that the insulation on the wire is intact all the way to where the connector will be crimped. If you are installing wiring connectors on an existing wire in the vehicle, it is usually a good idea to first inspect the wire for signs of breaks, cracking, or missing sections of insulation. If the insulation is missing or damaged anywhere on the length of wire, it may be best to replace the wire completely. If that is not possible or desirable, heat shrink or electrical tape can also be used to patch damaged insulation to prevent electrical arcing.
Once you’re sure the wire is in good condition and the insulation is intact, you are ready to strip the end of the wire. Wire stripping tools are available, and often have a variety of stripping blades dependent on the gauge of the wire. If you do not have a wire stripping tool available, you can also carefully use a razor blade or utility knife to cut about a quarter inch of the wire insulation. In emergency situations where you have no tools available, a lighter can also be used to melt the end of the wire insulation and remove it using your fingers. Be careful though, as the melted insulation will be hot and could cause burns to your fingers. For our purposes, we will describe how to properly use appropriate wire stripping tools to complete your repairs.
Once you’ve determined the gauge of the wire you are stripping, line it up with the appropriate stripping blade on your tool. Once the tool is clamped down and has cut through the wire insulation, grasp the rest of the wire with your other hand and pull the stripper to remove the end of the wire insulation. Using the wrong gauge of stripping blade could cause the wire’s copper core to be cut, or fail to cut the insulation at all, so it’s best to use the right size the first time to avoid losing any length on the bare end of the wire.
After the insulation has been removed, it may be necessary to twist the copper strands of the wire together. This not only makes it easier to insert the wire into a crimp fitting, but also helps you ensure the copper isn’t damaged or bent before you can finish your repair. Simply grab the end of the bare wire with your thumb and index finger and roll them together to spin and twist the copper core.
Now that you’ve stripped about a quarter inch of insulation from the end of the wire, you’re ready to install your wire connector and crimp it securely into place. You’ll need a wire crimping tool, which is usually built with three sizes of crimping jaws to accommodate the three varying sizes of wiring connectors that are most common. Determine the appropriate connector type and size for the wire and connections you are trying to make, then slide the connector over the end of the wire.
Once the connector is installed over the bare end of the wire, position your crimping tool’s jaws over the connector and squeeze to compress the connection. This will take a fair amount of force, but once you are satisfied with the crimp, you can remove the crimping pliers from the connection. At this point it is usually a good idea to test the sturdiness of the connection by pulling lightly on the wire and connector. If they separate, it may be necessary to try again and use more force when crimping. You may also need to check and make sure you are using the correct connector size for the wire.
Heat shrink is a final step in installing wiring connectors that can help waterproof the connection and prevent dirt and corrosion from causing high resistance or short-circuiting. Heat shrink does exactly what its name implies – it shrinks around the wire and connector when exposed to heat. Simply cut a piece to length and slip it over the connector and wire, then use a heat gun, hair dryer, or even short bursts of contact with a lighter until the heat shrink conforms to the wire and connector.
In some cases, especially when installing butt connectors or ring connectors, the heat shrink may need to be slid over the wire before the connector is crimped into place. Once the connector is installed, the heat shrink can be moved into position and heat applied to cover the connection. In other cases, connectors may be available with heat shrink built-in, and they can simply be installed and then shrank over the wire for a complete, waterproof repair.
Now that you know how to install crimped wiring connectors, we hope you will feel comfortable taking on your own basic electrical repairs. If you’d like to know more about electrical system diagnosis and repair, you can also check out our articles on how to use a multimeter, how to test and install a relay, and even how to install a light bar on your vehicle, all available in our How-To Hub. If you’re still not comfortable tackling your own electrical and wiring repairs, we would also be happy to recommend a local shop.