Mar 5, 2025
by Arik Vrobel
Author of the article
When designing a wire harness, even small CAD design errors can significantly impact manufacturing costs, production timelines, and the accuracy of price quotes from contract manufacturers. Many of these errors lead to increased material costs, longer lead times, and unnecessary manual labor, all of which can inflate pricing and cause delays in production.
To help avoid costly mistakes, here are 37 common errors in wire harness CAD design that impact price quotes from contract manufacturers—and what you can do to prevent them.
1-10: Design inconsistencies and ambiguities
One of the biggest challenges contract manufacturers (CMs) face is dealing with incomplete or conflicting design information. Any ambiguity in your CAD files or documentation can lead to incorrect assumptions, increasing quote variability and potential manufacturing issues.
Incomplete or missing wire lists – If the wire list isn’t fully detailed, manufacturers may need to manually determine missing specifications, increasing costs.
Inconsistent wire labeling – Mismatched labels can result in errors during assembly, requiring rework and extra verification steps.
Incorrect or missing BOM (Bill of Materials) – Without a complete and accurate BOM, price quotes will be based on assumptions rather than actual materials.
Undefined or vague specifications – Ambiguous requirements force CMs to make conservative estimates, often inflating costs.
Conflicting information in drawings and documentation – Discrepancies lead to back-and-forth communication, slowing down the quoting process.
Unclear revision control – Outdated or incorrect designs can be quoted incorrectly, leading to costly revisions.
Mismatched wire lengths between diagrams and harness layouts – Inaccurate wire lengths can lead to excess material waste and additional labor.
Lack of standard connector part numbers – CMs may substitute incorrect or higher-cost components if part numbers aren’t specified.
Improperly defined wire gauge or insulation type – Specifying incorrect gauges or insulation can lead to overengineering and unnecessary expenses.
Unspecified or unclear grounding requirements – Lack of grounding details can result in expensive design changes later in production.
11-20: Sourcing and component selection issues
Your choice of materials and components directly impacts the total cost of the harness. Using obsolete, unavailable, or unnecessarily high-cost components can cause sourcing issues and delays.
Specifying obsolete or unavailable components – This forces CMs to find costly alternatives, leading to increased quotes.
Using non-standard connectors – Custom or rare connectors drive up costs due to low availability and high MOQs (minimum order quantities).
Failing to account for MOQ (Minimum Order Quantities) – If a component requires bulk purchasing, costs per unit may rise significantly.
Specifying materials without alternatives – A lack of substitutes makes supply chains vulnerable to shortages, increasing risk and costs.
Not standardizing wire colors – Custom color codes may require special orders, raising procurement costs.
Incorrect or missing pinout information – Without clear pinout details, CMs may need additional engineering time, inflating costs.
Specifying high-cost materials where standard options would suffice – Overengineering components leads to unnecessary expenses.
Ignoring harness manufacturability in component selection – Some components complicate assembly, increasing labor and tooling costs.
Failing to indicate wire and cable bend radii – If bend radii aren’t considered, the design may require modifications, delaying production.
Using mismatched terminal and wire specifications – Improper pairings can lead to crimps failing quality checks, adding rework costs.
21-30: Manufacturing and assembly complications
A well-designed harness should be easy to manufacture and assemble. Overcomplicated designs increase labor time, errors, and overall costs.
Not optimizing wire routing for ease of assembly – Inefficient routing increases complexity, extending production time.
Overcomplicating harness layouts – Complex layouts with unnecessary crossovers and intersections make manufacturing inefficient.
Failing to specify sealing or environmental requirements – Missing details on IP ratings or environmental protections can lead to incorrect material choices.
Missing or unclear strain relief requirements – Without strain reliefs, cables may be prone to failure, leading to costly redesigns.
Not considering automated vs. manual assembly – Overly complex designs may prevent automation, increasing labor costs.
Specifying excessive wire lengths – Unoptimized wire lengths waste material and increase costs.
Failure to include retention features for connectors – Without these features, connectors may loosen or disconnect over time, causing field failures.
Ignoring crimp force or pull-test requirements – Weak crimps lead to electrical failures, increasing quality control costs.
Not defining wire twist requirements for signal integrity – Poorly defined twists can cause EMI issues, requiring additional shielding.
Not accounting for heat shrink or protective sleeving – Missing insulation requirements results in additional costs when adjustments are made later.
31-37: Costly oversights in documentation and communication
Beyond CAD design errors, the way you document and communicate your design can significantly impact quoting accuracy. Missing details or unclear specifications often result in higher quotes due to risk mitigation factors.
Lack of detailed test requirements – Without clear testing criteria, CMs may add unnecessary costs for assumed inspections.
Not specifying required certification standards (UL, IPC, MIL-SPEC, etc.) – Failing to define compliance requirements can lead to regulatory issues.
Ignoring packaging and shipping constraints – Oversized or poorly packed harnesses can increase handling and shipping costs.
Failure to identify special handling requirements – Fragile or sensitive harness components may require additional protective measures.
Unclear tolerance specifications for wire lengths and crimps – Tight tolerances can increase production complexity, adding costs.
Not providing 3D models or step files – Without 3D models, manufacturers may misinterpret design intent, leading to quoting inaccuracies.
Poor communication with contract manufacturers during quoting – Lack of collaboration results in incorrect assumptions, buffer pricing, and unnecessary delays.
Final thoughts: Reducing errors for better price quotes
A wire harness design riddled with errors or ambiguities leads to inflated quotes, unexpected costs, and delayed production. By addressing these 37 CAD design errors, you can improve the accuracy of price quotes, reduce supply chain risks, and streamline the entire manufacturing process.
