An automotive wiring harness is mainly composed of wires, connectors, wrapping tape and other auxiliary materials. It is the carrier that controls automotive signals and, with its complex structure and diverse functions, is known as the "nervous system" of the vehicle. The wiring harness is one of the most critical components inside a car, and its quality, safety and reliability are vital to vehicle quality. If a harness or connector fails, signal transmission may fail and functional equipment may stop working; contact resistance may become excessive and cause overheating or fire; a short circuit may cause a fire; or the insulation layer may fail and cause leakage. Therefore, to ensure the quality, safety and reliability of automotive harnesses and connectors, testing on the production line or before use by the customer is very important. Automotive harness and connector testing covers environmental testing, electrical performance testing and mechanical performance testing.

Automotive wiring harness test items

1. Scope of testing and analysis capabilities

Appearance and dimensions

Electrical performance tests, mechanical performance tests, environmental stress tests, VOC and hazardous substance testing

Electromagnetic compatibility (EMC)

Cleanliness testing

Metal material analysis of wiring harnesses and connectors

Non-metal material analysis of wiring harnesses and connectors

Failure analysis of wiring harnesses and connectors

2. Appearance and dimensions

Surface roughness

Profile parameters

Roundness

Cylindricity

Line profile

Surface profile

Parallelism

Perpendicularity

Angularity

Coaxiality

Symmetry

Position

Circular run-out

Total run-out

Shaft and hole parameters

Length

Width

Thickness

Diameter

3. Electrical performance tests

Dielectric strength

Insulation resistance

Low-level contact resistance

Shorting bar contact resistance

Contact resistance at rated current

Voltage drop

Electrical discontinuity

Temperature rise test

Current carrying capacity

Current cycling

LCR testing

Derating curve

Conductor resistance

Insulation volume resistivity

Withstand voltage

4. Mechanical performance tests

Terminal-to-terminal insertion and extraction force

Terminal bending resistance

Terminal-to-housing insertion force, push-out force and retention force

Terminal normal force

Connector mating and separation force

CPA and TPA insertion and extraction force

Mechanical strength of the locking device

Mechanical strength of the fixing structure

Mechanical strength of the assist mechanism

Poka-yoke structure of terminals and terminal cavities

Poka-yoke structure of connectors

Retention force of seals

Retention force of board-side pins

Insertion and extraction force of tractor electrical connectors

Inspection of the locking device of tractor electrical connectors

Ejection force of tractor electrical connectors

Strength of the locking device and cable fixing of tractor electrical connectors

Low-temperature shear strength of tractor electrical connectors

Static load of tractor electrical connectors

5. Mechanical performance tests (continued)

Fretting corrosion

Mating cycles

Audible click on full connector mating

Free fall

Tumbling test

Ferrule retention force (high-voltage connectors)

Vibration, mechanical shock and combined testing

Connector mating life

Crimp cross-section inspection

Cable peel force

Low-temperature cable winding

Cable impact

Cable abrasion resistance

Cable marking durability

Crimp strength between terminal and wire

Insulation crimp bend test

6. Environmental stress tests

High temperature

Low temperature

Constant damp heat

Damp heat cycling

Thermal shock

Rapid temperature change

Condensation

Continuous salt spray and cyclic salt spray

Mixed flowing gas

Ammonia vapour test

Chemical solution resistance

Full IP testing

Cable ozone resistance

Cable hot water resistance

Long-term and short-term heat ageing

Air tightness

UV ageing

Xenon lamp ageing

Ozone ageing

Fungal corrosion

Highly accelerated stress test (HAST)

Solderability

Resistance to soldering heat

Tin whisker growth

Reflow sensitivity

Fluid resistance

Water influence test

Air tightness test

7. Component-level VOC testing

Bag method VOC

Chamber method VOC

Material-level VOC testing

Odour testing

Fogging testing

Formaldehyde testing

Total carbon testing

Tube method testing

Micro-chamber testing

8. Hazardous substance testing - ELV

Restrictions are placed on the content and use of hazardous substances in all automotive parts and materials.

· Reduce the use of hazardous substances during vehicle design

· Vehicles placed on the market after 1 July 2003 must not contain Hg, Cd, Pb or Cr(VI), and the limits for banned components in all parts and materials apply (except as provided in the exemptions)

· Cadmium (Cd) ≤ 100 ppm (0.01%)

· Mercury (Hg) ≤ 1000 ppm (0.1%)

· Lead (Pb) ≤ 1000 ppm (0.1%)

· Hexavalent chromium (Cr VI) ≤ 1000 ppm (0.1%)

· PBB (polybrominated biphenyls) ≤ 1000 ppm (0.1%)

· PBDE (polybrominated diphenyl ethers) ≤ 1000 ppm (0.1%)

9. Electromagnetic compatibility (EMC)

Time-domain conducted disturbance on power lines

Frequency-domain conducted disturbance on power lines

Frequency-domain conducted disturbance on signal lines

Radiated disturbance - antenna reception method

Radiated disturbance - TEM cell method

Electromagnetic susceptibility (EMS)

Pulse immunity on power lines

Pulse immunity on signal lines

Direct RF power injection

Bulk current injection

Audio-frequency coupling immunity on power lines

Radiated immunity - antenna illumination method

Radiated immunity - TEM cell method

Radiated immunity - stripline method

Radiated immunity - magnetic field loop method

Electrostatic discharge testing

10. Cleanliness testing

Cleanliness refers to the degree to which specific parts of a component, assembly or complete machine are contaminated by impurities. It is expressed by the mass, size and number of impurity particles collected from specified characteristic locations using specified methods. "Specified locations" are those that jeopardise product reliability. "Impurities" include all impurities that remain from the product itself, are introduced from outside, or are generated by the system during design, manufacturing, transport, use and maintenance.

Reference standards:

ISO 16232 Road vehicles - Cleanliness of components of fluid circuits

VDA 19 Inspection of technical cleanliness - Particulate contamination of functionally relevant automotive components

PV 3370 Automatic transmissions and peripheral components - Testing for foreign contaminants

ISO 4406 Hydraulic fluid power - Fluids - Method for coding the level of contamination by solid particles

11. Metal material analysis of wiring harnesses and connectors

Fracture analysis

Weld inspection

Metallographic analysis

Coating analysis

Mechanical property analysis

Microscopic analysis

Corrosion analysis

Non-destructive testing analysis

12. Non-metal material analysis of wiring harnesses and connectors

Mechanical properties

Composition analysis

Thermal properties

Electrical properties of plastics

Flammability

13. Failure analysis of wiring harnesses and connectors

Failure analysis is a post-mortem analysis of products that have already failed. By using various test and analysis techniques and procedures it confirms the failure phenomenon, distinguishes the failure mode or mechanism, determines the ultimate cause and proposes improvements to the design and manufacturing process, so as to eliminate the failure and prevent recurrence and improve the reliability of electronic connectors. It is an important part of product reliability engineering.

Comprehensive failure analysis techniques:

Decapsulation and sampling

Cross section

Dye and pry

SEM and EDS

Finite element analysis (FEA)

Transmission electron microscopy (TEM)

Micro Raman spectroscopy

X-ray fluorescence spectroscopy (XRF)

Micro Fourier transform infrared analysis (FTIR)

Auger electron spectroscopy (AES)

Emission microscopy (EMMI)

X-ray transmission

Infrared thermography

X-ray diffraction (XRD)