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HomeTips & GuidesAutomotive Airbag Wire Harness: Components and Importance of Proper Design/Manufacturing

Automotive Airbag Wire Harness: Components and Importance of Proper Design/Manufacturing

Come here to learn more about the automotive airbag wire harness.

Airbags have become standard safety features in vehicles, and comparisons usually revolve around how many each car has on board. 

However, the underlying operating mechanism of this system uses an electric trigger to activate a chemical reaction to deploy the gas-filled safety bag.

Therefore, automotive airbag wire harnesses are critical in this system, and we’ll look at its design, manufacturing, installation, integration, and vital components. 

Table of Contents

How Airbags Work

Initially, airbags relied on a chemical reaction that involved breaking down sodium azide into sodium and nitrogen gas. 

The system also contains potassium nitrate and silicon dioxide.

Airbags primarily rely on crash sensors at the front of the vehicle. 

If they detect a collision, they trigger the sodium azide using an electrical charge, causing it to explode.

Parts of an airbag with electric wires and plugs

Parts of an airbag with electric wires and plugs

During this explosion, sodium azide breaks down using this formula.

2NaN3 → 2Na + 3N2

However, sodium metal can react with air to form sodium hydroxide, a corrosive chemical to body tissues. 

But potassium nitrate reacts with this metal to produce an additional molar equivalent of nitrogen gas.

10Na + 2KNO3 → K2O + 5Na2O + N2

Silicon dioxide reacts with these compounds further to convert them to the more inert sodium silicate and potassium silicate.

K2O + Na2O + 2SiO2 → K2SiO3 + Na2SiO3

These chemical reactions characterized the first-generation airbags. 

Current airbag systems feature guanidine nitrate and a copper nitrate oxidizer because the chemicals are less toxic.

But both reactions produce nitrogen gas, which fills the bag to cushion you during impact.

Current vehicles incorporate compressed gas (argon or argon-helium) to deploy side curtain airbags, while others use hybrid systems that combine compressed gas with chemical reactions.

Reaction Time

Average automobile collisions take about 200 ms (twice as long as it takes to blink). So, the triggering mechanism must act fast to initiate the chemical reaction.

Usually, the airbag deployment decision based on crash sensor data takes about 10-30 ms, and the bags deploy fully within 60-80 ms. 

So, the process takes less time than the blinking speed, making it highly effective during crashes.

Airbag Components

Modern airbag systems feature these components.

  • Airbag inflator (chemical reactor)
  • Airbag module (housing)
  • Diagnostic module (control unit)
  • Airbag fabric
  • Crash sensors
  • Impact sensors
  • Airbag cushion
  • Cable harness

We are interested in the airbag wire harnesses, which interconnect the electrical components of this system. 

These include crash sensors, the diagnostic module, and impact sensors.

Airbag Wiring Components

Car wire harnesses have some similarities, but the airbag’s electrical connection is slightly different because it features these components.

Wires

Wires form the conductive circuits that transmit electrical signals for power or communication across the sensors and control unit.

Loop wires for linking the steering column stalk airbags

Loop wires for linking the steering column stalk airbags

Wiring Connectors

These components ensure secure wire attachment to system parts, and they are either terminals, sockets, or plugs.

Sensor Connectors

The airbag system features sensors like crash, impact, and seatbelt. 

Some even have MEMS sensors to measure the crash’s severity, while others monitor gyroscopes, wheel speed, seat occupancy, and brake pressure sensors.

A vehicle with a deployed driver-side airbag

A vehicle with a deployed driver-side airbag

All these components require specialized connectors to transmit the sensor reading.

Airbag Inflator Connector

This component houses the chemicals that explode to produce nitrogen gas to fill the airbag. 

The chemicals need an electrical trigger to initiate the reaction, and this connector provides the electrical link to activate the trigger.

Air Bag Module Connector

Airbag modules house the system, and this connector facilitates signal communication from the control unit to coordinate deployment.

Locking Mechanisms

Some critical airbag wire harness connectors have locking mechanisms to ensure they remain connected during impact. Failure of these connector links can be fatal.

Backup Power Supply

Significant frontal impacts can cut the battery cable supplying power to the airbag system, rendering it useless. 

Therefore, it needs a backup power supply, usually in capacitor form, to ensure the chemical reaction or compressed gas activates to fill the bag.

A disassembled steering wheel with the airbag removed

A disassembled steering wheel with the airbag removed

Clips and Retainers

These components fix the airbag harness to the vehicle, preventing tangling or chafing from other car parts.

Service Loops

Service loops are additional wire lengths on the harness that enable servicing or cable repair without having to do a complete wire harness replacement.

Diagnostic Ports

Airbag systems need periodic system checks to ensure they are still functional or updates to make them better. 

Diagnostic ports enable technicians to access this safety feature, usually via the OBD port.

Sheath

Airbag wire harnesses need firm sheaths to safeguard the conductors from collision damage or environmental factors. 

These wires should remain intact as the vehicle ages to ensure the airbag system remains functional. 

So, sturdy wiring insulation is crucial.

Importance of Proper Air Bag Wiring Harness Design and Manufacturing

Proper airbag wire harness design and manufacturing are critical for these reasons.

Ensures Vehicle Occupant Safety

The airbag system is only as effective as the wires interlinking the control unit, sensors, inflator, and module. 

A well-designed and manufactured electrical wiring harness ensures quick and reliable signal transmission, leading to timely deployment if the sensors detect a crash.

A technician removing the driver-side airbag

A technician removing the driver-side airbag

Timing is of the essence when dealing with these systems, and the electrical circuit is crucial in ensuring precise deployment.

Eliminates False Deployment

Signal interference can cause false airbag deployment, so you must design and manufacture the harnesses to resist interference from electrical noise and vibrations.

Although airbags help save lives during impact, they can cause serious injury if they deploy accidentally.

Enhances System Reliability

If you are a careful driver, you can use your vehicle for years without having an accident. 

But it can happen anytime after several years, and the system better be as effective as when the car was new.

A well-designed and manufactured wire harness will resist degradation from extreme temperatures, moisture, vibrations, etc., making the airbag system fully operational.

Ensures Compliance With Safety Standards

In the US, regulatory agencies like the NHTSA (National Highway Traffic Safety Administration) have strict automotive airbag system safety standards.

Proper design and manufacturing ensure the systems meet these rigorous standards before installing them in vehicles.

Cuts Costs

Proper design and manufacturing processes can optimize material usage during production and reduce complexity.

 This combination will cut production costs while maintaining the electrical wire harness quality.

Enables Seamless System Integration

Modern cars feature multiple electronic components and a complex wiring system. 

Proper airbag wire harness design and manufacturing will ensure this system integrates with the other electronics seamlessly to ensure timely monitoring and airbag deployment.

An airbag system

An airbag system

Importance of Proper Airbag System Wiring Harness Installation and Integration

Proper airbag wiring harness installation and integration give similar benefits to the ones for design and manufacturing but with these two additions.

Simplifies Serviceability

A well-installed and integrated airbag wire harness simplifies maintenance and servicing because it covers labeling, color coding, etc. 

So, technicians won’t cause further system damage, including false deployment due to incorrect wiring.

Enables Quick Testing and Validation

Vehicle makers must test and validate an airbag system after installation and integration. 

When carried out correctly, the wires and connectors will be in place and secure, making the car pass the test quickly.

And even if there are installation or integration issues, a proper installation will make it easy to spot the issue.

Wrap Up

Although they were luxury features initially, airbags have become essential safety features. 

Even basic vehicles have at least the driver airbag to give safety to the person at the wheel.

Automotive airbag wire harnesses are the nerves that make this system operate effectively. 

So, they need proper design, manufacturing, installation, and integration to keep you safe if you have an accident.

Check out this article to learn more about the auto wire-harness management process to enhance this cable and other vehicle wires. That’s it for now. Have a good one!

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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