Guide to Cable and Connector Selection for Automotive Engineering

Apr 1, 2024

Having worked on 100’s of automotive designs, I've seen how the selection of cables and connectors can make or break the functionality and reliability of a vehicle's electrical system.

Have you ever considered how critical the right choice of cables and connectors is for safety and performance? How often do you assess the compatibility of your chosen components with the overall vehicle architecture? This guide will provide you with a step-by-step approach to cable and connector selection tailored for automotive engineering projects.

Step 1: Define the Application Requirements

Start by understanding the electrical and mechanical requirements of your application. What are the current and voltage requirements? What temperatures and environmental conditions will the cables and connectors be exposed to? Automotive environments can be harsh, with temperature fluctuations and exposure to fluids and chemicals. Ensure the materials selected can withstand these conditions.

Step 2: Select the Wire Type

Choose the wire type based on the application needs. For power transmission, thicker gauge wires are typically required. For signal transmission, twisted pair or shielded cables may be necessary to prevent electromagnetic interference. Automotive grade wires, such as those meeting SAE J1128 standards, are designed for vehicle use.

Step 3: Determine the Wire Size

The wire size is critical for ensuring that the cable can handle the required current without overheating. Use the American Wire Gauge (AWG) system as a standard. A wire's current-carrying capacity, or ampacity, should be checked against the expected load. Over-specifying can lead to unnecessary cost and weight, while under-specifying can be a safety hazard.

Step 4: Choose the Insulation Material

Select an insulation material that can withstand the operating environment. Common materials for automotive applications include cross-linked polyethylene (XLPE) and polyvinyl chloride (PVC). Consider factors like temperature resistance, flexibility, and abrasion resistance.

Step 5: Connector Selection

Connectors must be reliable and suited to the environment. They should have a secure locking mechanism and be rated for the correct current and voltage. Automotive connectors often need to meet specific standards, such as those from the International Organization for Standardization (ISO) or SAE International.

Step 6: Evaluate the Connector Housing

The housing material should protect against environmental factors such as moisture, dust, and chemicals. Materials like nylon and PBT are common for their durability and resistance to automotive fluids.

Step 7: Consider the Contact Material

Contacts within connectors should be made from materials that provide good electrical conductivity and corrosion resistance, such as gold-plated or tin-plated brass or copper alloys.

Step 8: Assess the Sealing Requirements

For connectors exposed to the elements, proper sealing is essential. Look for connectors with appropriate IP (Ingress Protection) ratings that indicate their resistance to dust and water ingress.

Step 9: Mechanical Fit and Locking Mechanism

Ensure that connectors fit securely and have a reliable locking mechanism to prevent accidental disconnection due to vibration, which is common in automotive applications.

Step 10: Compliance with Standards

Verify that the selected cables and connectors comply with automotive standards such as ISO, SAE, and specific OEM (Original Equipment Manufacturer) requirements.

Step 11: Prototyping and Testing

Before finalizing the design, create prototypes and test them under actual operating conditions. This helps identify any issues with the cable or connector selection.

Step 12: Validation for Common Errors

Use software solutions to validate the design for common errors. Is the connector properly seated? Are there any risks of shorts or breaks in the wire due to bending or fatigue?

Step 13: Finalize Design and Documentation

Once testing and validation are complete, finalize the design. Ensure that all specifications and selections are well-documented for future reference and manufacturing.

Wrapping up, the selection of cables and connectors is a critical aspect of automotive wire harness design. A methodical approach ensures that the electrical wire harnesses meet the necessary specifications and perform reliably in the automotive environment. By adhering to this step-by-step guide, engineers can avoid common pitfalls and ensure that their designs are robust, efficient, and safe.

Given the importance of this process, it's crucial to ask: Are the selected components optimized for cost and performance? Have all environmental factors been considered in the selection process?

Remember, the earlier potential errors are identified in the design or pre-production process, the less impact they will have on the schedule and cost. This proactive approach is essential for wire harness manufacturers across all industries, including automotive, aerospace, industrial, vehicle, medical, and machinery sectors.