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HomeTips & GuidesAutomotive Wire Harness Connector Types: How Do They Differ?

Automotive Wire Harness Connector Types: How Do They Differ?

In this article, we will look at the various automotive wire harness connector types.

Car wire harnesses cannot run continuously throughout the vehicle. They must have ends or terminations where they connect with other components or wires. 

Connectors ensure these joints transmit electric signals without affecting their integrity.

Let’s look at the wire harness connector types below to understand how they differ.

Table of Contents

What Is an Automotive Wire Harness Connector?

Automotive wiring harnesses are organized sets of wires with terminations at the end to provide connection points.

So as the name suggests, automotive wire harness connectors are plugs or sockets that link wire harness to wire harness, device to wire harness, board to wire, etc., via the terminations.

Plug refers to a male connector, while socket refers to a female connector. In most cases, you’ll find the latter fixed in position, but the male connector is movable.

And the connector’s performance directly impacts the harness’ electrical performance. 

Since harnesses supply power and data signals to various car components and sensors, the integrity of the connector determines your safety when driving the vehicle.

A male and female connector (plug and socket)

A male and female connector (plug and socket)

If it fails, the signals might not reach the destination. Or they might get corrupted, resulting in wrong sensor data or other errors.

Automotive Wire Harness Connector Parts

Cars have an average of about 274 connectors, and most have these four parts.

Automotive Wire Harness Connector Types: Shell

The shell is the outer frame that locks the two halves (plug and socket) together. Its primary purpose is to provide mechanical protection to the components inside.

So it must remain dimensionally stable when exposed to extreme temperatures and chemical changes.

Automotive Wire Harness Connector Types: Pins and Sockets

Male connectors contain pins that fit inside pin receptacles when you plug them into the female connector.

Once connected, these metal contact points transmit electric current across the harnesses or into and out of the connected device.

Automotive male and female connectors

Automotive male and female connectors


The wire harness connector shell cannot hold the other connector reliably. Retainers help keep the joint locked to keep the electricity flowing uninterrupted. It can either be a tiny piece of plastic or a metal clip.


Each connector has a rubber seal that surrounds the wires and keeps water from flowing into the electrical joint. Seals also help arrange the contacts in the required position and with the correct spacing.

Automotive Wire Harness Connector Types

Automotive Connectors generally fall into these categories when considering the wire harness design.

A Group

This group covers all connectors that link the head unit to its power supply, antennas, switches, and volume controls.

B Group

B-group automotive connectors provide electrical links between the head unit and the car speakers. So you can call them audio connectors.

Car audio wiring with its connector

Car audio wiring with its connector

C Group

These connectors provide electrical links with other peripheral devices linked to the head unit, including CD decks, remote controls, amplifiers, etc.

D Group

D-group connectors also link to the head unit, but specifically from satnav systems.

Multi-Pin Sealed Connector

All 2-pin, 3-pin, 6-pin, 8-pin connectors, etc., fall under this classification, provided they have a sealed enclosure.

Several multi-pin sealed connectors

Several multi-pin sealed connectors

Terminal Connector

Terminal connections rely on screws to connect stripped wire ends on both sides. Instead of tying the wire ends together and wrapping the joint using insulation tape, terminal connectors keep the joint neat. And they are ideal for wire harnesses because they have multiple ports to connect several individual wires.

Terminal connectors

Terminal connectors

Wire-to-Wire Connector

These connectors link two wire harnesses that have terminated cables, creating a lengthier bunch for electrical or signal transmission.

Most of them are sockets that connect two male-terminated wire harnesses.

Wire-to-Board Connector

These connectors create links between wire harnesses and car computer circuit boards. Most boards have built-in connectors, so you only have to plug in and secure the male connector from the wire harness.

Board-to-Board Connector

As the name suggests, board-to-board connectors link two car circuit boards together. Some of these pinned connectors plug into both boards with no wires in between.
But if you need some flexibility or space between the boards, you can have a short harness with plug-terminated ends to link the PCBs.

Seamless Connector

These crimp-style connectors look like tubes because they are initially round stock that gets cut into tiny pieces. To create a joint, slide the stripped wires from both ends, then crimp the connector to grip the metal wire strands inside.

Crimped seamless connectors

Crimped seamless connectors

You should pick a connector that matches the wire size to make the joint appear seamless. Also, the right size will ensure the crimped metal grips the wire inside.

Butt connectors fall into this category and can be either of the following.

  • Heat shrink butt splice connectors
  • Non-insulated butt connectors
  • Vinyl-insulated butt splices
  • High-temperature butt connector
  • Nylon-insulated butt splices
Insulated butt connectors

Insulated butt connectors

Seam Type Connector

Wires are generally round, which explains why they form seamless connections with round seamless connectors. The seam type is also round, but it starts as flat stock.

So the seamless design does not refer to the shape. It refers to the continuity of the round enclosure around the wires.

Seam type connectors

The flat stock takes the form of a tube after rolling but has a seam or line opening across the connector’s length.

So when crimping this connector, the outer shell can slide over each other along the seam to tighten the grip on the connected wires.

Insulated Connector

These connectors can have straight or flared ends and come in different shapes and sizes.

The wire and its insulation should fit inside the connector for full coverage. This way, no water will get in.

Non-Insulated Connector

This category covers all connectors that don’t have a protective jacket. Most seam-type and seamless connectors have non-insulated shells, meaning you need heat-shrink tubing to cover the exposed metal.

AWG Distribution Type Connector

A distinct characteristic of these connectors is that they are huge and can handle high electric current levels.

So you can find them in battery packs, charging ports (electric cars), and other high-current automotive applications. And they come in up to 4 AWG ratings.

Heat Shrinkable Insulated Connector

These connectors come with insulative tubings that respond to heat by shrinking. You only need a heat gun to shrink the material after the harness connection.

Although expensive, this type is one of the best connectors due to its waterproof cover. And you can use it for marine applications, as well.

Heat-shrinkable tubes insulating electrical wires

Heat-shrinkable tubes insulating electrical wires

Temperature, Vibration, and Sealing Classification

Other connector classifications exist based on temperature, vibration, and sealing performance.

But this categorization depends on the acceptable standards per country or region. For instance, we have these classes when using USCAR (North America).


  • T1 (-40 to 85°C): Not recommended for new applications
  • T2 (-40 to 100°C): Ideal to use in the passenger component
  • T3 (-40 to 125°C): Suitable for the engine component
  • T4 (-40 to 150°C): Ideal to use in the engine near hot sections
  • T5 (-40 to 175°C): For use as needed


  • V1 (chassis profile): Connect harnesses on sprung car parts not linked to the engine
  • V2 (engine profile): Link harnesses coupled to the motor that experience minimal vibrations
  • V3 (severe on-engine): Connect harnesses to serve in vibration areas
  • V4 (extreme vibration): Link wires in high-vibration areas
  • V5 (unsprung): Ideal for wheel-mounted components


  • S1 (unsealed): Ideal for joining harnesses in the passenger component or the trunk (dry areas)
  • S2 (sealed): Suitable for connecting harnesses in exposed areas like engine bays and doors
  • S3 (high-pressure spray seal): Ideal for areas exposed to high pressure

Wrap Up

Automotive wire harness connectors don’t fall into single categories. They have several features like insulation, seams, and number of pins that make their classification a bit complicated. 

But the article above should help you grasp these differences. And if anything seems unclear, reach out. We’ll clarify it for you asap.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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