Publish Time: 2026-07-30 Origin: Site
A failed EV high-voltage wiring harness can cause connector overheating, insulation breakdown, power loss, vehicle shutdown, or a costly safety recall.
The most effective solution is to control terminal resistance, cable routing, sealing, shielding, and assembly quality as one complete high-voltage system. Most failures begin at crimps, connectors, seals, sharp routing points, or poorly controlled interfaces rather than in the middle of a healthy cable.
DCT high-voltage interconnect solutions designed for electric vehicle power systems. Image source: Aptiv .[2]
A weak crimp, incomplete mating, damaged terminal, or contaminated contact surface increases resistance and can generate enough heat to melt the connector housing.
The solution is to control crimp height, conductor insertion, terminal locking, contact resistance, and connector position during production. Temperature-rise testing must use the real cable size, current profile, ambient temperature, and duty cycle instead of relying only on catalog ratings.
Connector position assurance and HVIL can help detect an incomplete connection. However, HVIL cannot prevent overheating caused by a high-resistance crimp that remains electrically connected.
A high-voltage cable routed across a sharp edge or installed under excessive tension can wear through its insulation and create leakage current, isolation faults, or a direct short circuit.
The correct solution is to control bend radius, clip spacing, strain relief, abrasion protection, and separation from moving or high-temperature components. Routing must also allow for battery-pack movement, vibration, thermal expansion, and vehicle servicing.
Damaged seals or incorrectly assembled backshells can allow water, salt, or coolant to corrode terminals and shielding interfaces. The complete mated connector should be validated for the actual installation environment rather than relying on the seal specification alone.
Failure Cause |
Possible Result |
Recommended Control |
|---|---|---|
High contact resistance |
Terminal overheating or melting |
Crimp monitoring and temperature-rise testing |
Incorrect cable routing |
Abrasion and insulation breakdown |
Controlled bend radius, clips, and edge protection |
Seal damage |
Water ingress and terminal corrosion |
Seal inspection and assembled-harness leak testing |
Broken shield continuity |
EMI and unstable electronics |
Shield resistance and continuity testing |
Incomplete connector mating |
Intermittent power or arcing risk |
HVIL, CPA, locking, and visual verification |
An interrupted shield, poorly terminated braid, or damaged HVIL circuit can cause electromagnetic interference, false fault signals, or unexpected high-voltage shutdown.
The solution is to test shield continuity, shield resistance, HVIL operation, insulation resistance, and dielectric strength on the complete harness. Shielding should remain continuous through the cable, connector, backshell, and equipment interface.
ZVEI guidance covers testing high-voltage wiring harnesses containing shielded cables, mechanical components, and contacting systems.[1] Validation should be repeated after vibration, thermal cycling, bending, fluid exposure, and environmental aging.
ISO 19642-9 defines requirements for screened and unscreened automotive copper cables used in high-voltage road-vehicle applications.[3] A compliant cable can still fail when its crimp, seal, connector, or routing process is uncontrolled.
Need a High-Voltage Harness Failure Review?
Send your voltage, current, cable size, connector model, failure photos, temperature data, routing drawing, and test conditions for a practical root-cause review or prototype recommendation.
High-resistance connections caused by poor crimping, incomplete mating, contamination, or terminal damage are among the most serious causes.
Yes. Vibration can loosen connectors, fatigue conductors, damage seals, and wear insulation against clips or metal edges.
Common causes include damaged insulation, water ingress, conductive contamination, connector corrosion, or contact between the cable and vehicle body.
No. HVIL detects an open or improperly connected circuit, but it cannot detect every overheating, sealing, shielding, or insulation problem.
15-Year Automotive Wire Harness Failure Analysis
Based on 15 years of automotive wire harness experience, I rarely treat a failed high-voltage cable as an isolated material problem. The real root cause is usually found at the interface between the cable, crimp, connector, seal, shield, clip, and vehicle routing.
[1] ZVEI — Tests on High-Voltage Wiring Harnesses for Motor Vehicles