Auto Wire Harness Parts: Everything You Need to Know

Like the blood vessels and nerves in the human body, the wiring harness is a vital vehicle component through which your car receives electricity and signals. So, it’s essential to ensure it’s in good condition to avoid all the stress. So, it’s a bad idea to skimp on your automotive wire harness. On the contrary, professionals advise investing in a properly designed and integrated harness made of quality materials and fully functioning auto wire harness parts. It will ensure you get the best out of your wire harness.

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Types of Auto Wire Harness Components

Below are the various types of auto wire harness parts:


Automotive wiring relays are used for high-load circuits that simple switches can’t handle and would probably burn out over time. A relay works as an electrical activation switch designed especially for high current courses. 

Typically, relays create a more powerful current using a low current signal from a switch. Should the relay burn out, you need not worry as it doesn’t cost much and is easy to replace.


Fuses act as sacrificial circuits designed to burn out when the maximum current level is exceeded. For instance, if a 10-amp fuse carries a current higher than 10 amps, it will likely burn out. 

The fuse protects electric accessories from damage in case of a short circuit in the harness. It’s crucial to ensure that all the courses in your saddle have fuses to protect your car’s harness from electrical fires resulting from a circuit burning out.

In the past, automotive electrical systems used glass fuses. However, today, most systems use blade fuses. They’re cheaper, more reliable, and easier to read since they’re color-coded to indicate the fuse’s amperage. 

Aircraft Wire Harness:  Glass fuses

Glass fuses

Fuse Block

The fuse block is the primary point where all fuses are stored. That way, if an electrical accessory is faulty, it’s easy to locate its fuse. 

Connectors and Terminals

The connector is a metal that connects a wire to another wire, switch, or fuse block. Depending on the intended application, there are various connectors, from simple to complex. Most connectors are brass or copper because they’re more resistant to oxidation and have higher conductivity than aluminum.

Although aluminum is conductive, it quickly oxidizes, forming a layer of oxide with low conductivity. However, aluminum is still widely used in many automotive industries to make connectors since it’s cheaper to acquire.

Wires are connected to the fuse in different ways. Many wire harness manufacturers use crimping, although some prefer crimping and soldering due to the added durability and conductivity.


Most harnesses are made of copper blend wire as it’s more cost-effective. However, modern OEM (Original Equipment Manufacturer) harnesses use pure copper wires because it has better conductivity. The wire itself is also a core component in designing a quality harness. 

Blended wiring functions as the resistor to drop voltage over more extraordinary lengths. 


Grommets are insulators whose function is to keep moisture out of the connector. You can attach grommets to a terminal or part of the connector.

Aircraft Wire Harness:  Grommet


Aircraft Wire Harness: Strain Relief 

Strain relief is typically added to the outer part of the connector to prevent force from pulling the wires in the connector. If the cables get removed, the terminal could pull out of the connector, causing a bad connection. 

If an outer bend radius poses a threat, you can add strain relief to help mitigate the force on the wire and terminal.

Aircraft Wire Harness: Ties 

Clamps and cable ties ensure the harness’ inner wires are attached to form a stream of wires moving in a specific direction. You can also connect them to a structure at particular points, minimizing movement.   

Aircraft Wire Harness: Locks

To prevent terminals on the wire from getting pulled out of the connector, you place locks in the connector. Locks also help ensure the complete insertion of the airport into the connector.

Aircraft Wire Harness: Marking

At the ends of the wire harness are numbers and symbols to help identify the connection of the wire object. These markings guide operators to properly connect corresponding wires and electronic devices. In addition, the marks help operators perform replacements or repairs to the wire harness. 

Often circuits have different colors to enable telling them apart. The wire color is mainly divided into multiple-color and single-color wires. The colors are usually standard, depending on the car factory.

Aircraft Wire Harness: Outer Coverings/Insulators/Wrapping

Outer coverings or insulators are sometimes called tubes and sleeves as they’re insulators that provide abrasion resistance, protection from electrical shock, and safeguard the environment.

Depending on the various parts and their use, the surface of the wire harness is wrapped differently. 

Since the engine part of the harness works under harsh conditions, it’s wrapped in a more robust, waterproof, flame-retardant, and highly mechanical-threaded pipe. 

The front cabin wire is also exposed to a relatively harsh environment. Therefore, many branches are wrapped in the high mechanical threaded pipe and some in PVC pipe.

The instrument line works in a relatively polite environment and covers a small space. It’s often wrapped with tape or flower wrap.

The door and headliner lines also have a limited workspace; you can wrap the branches in tape or plastic. However, using sponge tape, you can directly glue the more OK headliner line to the body.

The chassis line faces more contact with the body of the car. Therefore, it’s wrapped to prevent damage to the harness wear. 

How to Choose Your Auto Wiring Harness Components

All its components must work perfectly for a wiring harness to function effectively. However, there are some factors to consider when choosing parts for your wiring harness, including:

Aircraft Wire Harness: Where Will Your Wire Harness be Used?

The instrument panel mainly serves as the primary part of the entire wiring harness of the car, with the rest of the components extending from it. It’s divided into three main sections:

  • Front wiring harness: The front harness comprises the engine harnesses, battery, instrumentation, front light assembly, and air conditioning. 
  • Roof wiring harness: This harness comprises the audio speakers, roof light, and door.   
  • Back wiring harness: The rear harness contains the license plate light, brake light assembly, and luggage compartment lighting

All in all, the accessories in your car will determine the number of circuits needed for the wiring harness.

A wire harness can have different components with multiple ends and branches, a variety of wires headed in different directions, and several terminations on every unit. The wire harness uses electrical signals to allocate, direct, and relay information throughout the system. Therefore, you decide on the parts to use based on what’s required. 

For example, using HID headlights or fans with higher amperes, often unnecessary to other circuits, poses a threat to your relays. 

What Conditions Will Your Equipment Need to Endure

Environmental conditions are a significant consideration when choosing the components the wiring harness will use. The two main factors to keep in mind are:

  • Where you’ll use the wiring harness, indoors or outdoors?
  • Will any of the wiring harness parts be exposed to chemicals or moisture?

After all the considerations, you can decide on the following qualities:

  • Current and voltage capacities
  • The gauge, length, and material of the wire
  • Safety certification which includes any necessary industry-specific regulations and safety guidelines
  • The conductor, insulation, and sheath material
  • Organization of the assembly 


It’s essential to keep in mind the above considerations, especially during the product design phase. Choosing the best electronic components guarantees that your product runs without issues. That’s why picking an experienced OEM for your product is critical. 

At Cloom Tech, our large selection of wire harness components from leading manufacturers ensures the job gets done well. Our members apply to all sectors, including defense, automotive, marine, aerospace, and industrial. We provide that all our products are carefully picked to meet all your requirements and any international specifications and applicable industry standards. Also, all our products undergo extensive testing to ensure quality.

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Explore our custom services now. Email us at [email protected] for more details.

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