Japanese standard low voltage wires (especially AV, AVS and AVSS series) play an important role in automotive wiring harness design and manufacturing. They are used in Japanese cars and motorcycles low voltage circuits and some vehicles in the Southeast Asian market and are in accordance with the relevant JIS and JASO standards. The thin-walled wire has become mainstream due to limited wiring harness space and the recent trend of automobile electrification. Based on the information released publicly, in the article we will systematically introduce the definition, structural difference, performance comparison and application scenario of the three kinds of wires, so as to help the engineers and purchasing personnel to make accurate selection.
Naming and Standards Foundation
The naming logic for Japanese standard automotive low-voltage wires is clear:
A: Automotive (low-voltage wires for automobiles)
V: Vinyl (PVC insulation)
S: Thin wall
SS: Super thin wall
The specific correspondences are as follows:
AV
WIREs
PVC insulated low-voltage wires for automobiles, mainly conforming to JIS C 3406 standard, belonging to the more traditional thick-walled or standard-thickness type.
AVS
WIREs
Thin-walled low-voltage wires for automobiles (thin-wall type 1), conforming to JASO D611 (or related D625, etc.) standard.
AVSS
WIREs
Super thin-walled low-voltage wires for automobiles (thin-wall type 2), also mainly based on JASO D611, a further thinner version of AVS.
All three types of wires use annealed soft copper stranded conductors + PVC insulation, and the rated voltage is usually low voltage (about 50V AC / 60V DC). The operating temperature range is mostly -40℃ to 80℃ or 85℃ (some products are marked as intermittently up to 120℃), and they comply with RoHS and other environmental protection requirements. Lead-free designs are common.
Key difference: Insulation thickness determines performance and application
The biggest difference among the three lies in the thickness of the insulation layer, which directly leads to differences in outer diameter, weight, flexibility, and wear resistance.
| Type | Insulation thickness characteristics | Typical outer diameter | Flexibility | Abrasion resistance/protection | Weight and space occupancy |
|
AV |
Thicker | Larger | General | Better | Heavy and takes up a lot of space |
|
AVS |
Thin-walled | Medium | Better | Medium | Medium |
|
AVSS |
Ultra-thin wall | Minimum | Best | Relatively weak | Lightest and most space-saving |
Reference data (using common specifications as examples; actual specifications may vary depending on manufacturer standards):
0.5mm² AVS: Insulation thickness approximately 0.5mm, outer diameter approximately 2.0-2.1mm.
0.5mm² AVSS: Insulation thickness approximately 0.3mm, outer diameter approximately 1.6-1.7mm.
Conductor structures are mostly 7/0.32 or finer flexible structures (marked with "f" indicates finer stranded wire with better flexibility).
AVSS achieves lightweight and smaller diameter wiring harnesses by further thinning the insulation, which is particularly advantageous for high-density wiring in modern automobiles (such as dashboards, doors, and the area around complex ECUs). AVS strikes a balance between protection and cost. AV, as an earlier or specific product, has thicker walls and stronger mechanical protection, but it has been gradually replaced by thinner-walled series.
Application scenario comparison
1. For general low-voltage circuits in vehicles (instrumentation, lighting, audio, switches, etc.): AVS is the preferred choice. It withstands less extreme temperatures and oil contamination, has a moderate cost, and its insulation thickness is sufficient for everyday wear resistance and insulation protection. For example, in the instrument panel wiring harness of a compact car, 0.75mm² AVS can meet the low current requirements of the audio system and ambient lighting.
2. For high-density wiring harnesses with extremely limited space (door wiring harnesses, complex instrument assemblies, compact motorcycle wiring): AVSS is the preferred option. It has a smaller outer diameter and lighter weight, allowing for more circuits to be arranged in limited space while maintaining good bending performance. It is suitable for door wiring harnesses that are frequently opened and closed or for weight-sensitive two-wheeled vehicles.
3. For applications requiring some mechanical protection or traditional designs: AV still has its uses, especially in vehicles with high wear requirements or those using older standards. If the ambient temperature is higher or oil resistance is required, upgrading to cross-linked types (such as AVX, AEX, etc., with temperature resistance up to 100℃ or higher) can be considered, but this is beyond the scope of the AV series discussed in this article.
Practical Selection Recommendations
Consider temperature, oil contamination, vibration, cost, and space comprehensively.
Note that the "f" soft-structure version can further improve bending life and is suitable for dynamic areas.
In oily, high-temperature environments such as near the engine compartment or hydraulic equipment, prioritize assessing whether higher-grade wiring is required; in dry, normal-temperature environments inside the vehicle, AVS offers high cost-effectiveness; for extreme space optimization, choose AVSS.
Performance advantages and precautions
1. General Benefits:
PVC insulation is inexpensive, easy to work with and comes in many colors (which makes it easy to identify the wiring harness).
It meets the basic automotive requirements of vibration resistance, cold resistance and flame retardancy.
It allows for several colors and markings (ring marking or printing) to aid in production and maintenance.
2. Thin-wall insulation pros and cons: AVSS's ultra-thin construction significantly reduces the overall size and weight of the wire harness, aligning with automotive trends of lightweighting and electrification. But thinner insulation requires more attention to scratch and sharp-edge protection during installation, so appropriate sheathing, corrugated tubing, or wiring path design is needed. Monitoring of manufacturer test data for insulation degradation in thin walled products is required for long term high temperature use.
3. Common Specification Range: 0.3mm² to 5mm² or even larger. Conductor resistance (20℃) varies with cross-sectional area (e.g., approximately 32.7mΩ/m for 0.5mm²). Current carrying capacity should refer to standards such as JASO D609 and be calculated in conjunction with ambient temperature.
Summary and Selection Tips
AV, AVS and AVSS are the evolution of Japanese standard automotive low voltage wiring harnesses from standard wall thickness to ultra-thin wall thickness. AV is for conventional protection . AVS is for cost-performance balance . AVSS is for light weight design and space optimization . Today, AVS and AVSS have become the mainstream in automotive wiring harness design.
Selection recommendations:
1 Define operating temperature, current, space and environmental factors (oil contamination, vibration)
2 Check the outside diameter, wall thickness and certification details of the specific manufacturer (these vary slightly between manufacturers).
3 Give priority to lead-free and RoHS compliant products.
Further optimization of complex wiring harnesses is possible by combining variants such as CAVS (compressed conductor).
As automotive electronic density continues to increase, thin-walled wire technology is still evolving (e.g., higher temperature resistance, halogen-free versions). Understanding these fundamental differences can help avoid common problems such as "choosing the wrong wire leading to insufficient space or inadequate protection," improving wiring harness reliability and overall vehicle competitiveness.
