High-voltage Interlock Loop (HVIL)
The high-voltage interlock loop is a safety circuit that switches off high voltage if a connector is opened.
What is High-voltage Interlock Loop (HVIL)?
A low-voltage loop runs through HV connectors. Opening a connector breaks the loop. The system then opens the contactors. The loop is part of the functional safety design required for high-voltage systems. Workshops see HVIL faults after work on connectors, after water ingress or when a connector has not clicked fully into place. Diagnosis follows the loop through each connector using wiring diagrams.
How it works
The control unit monitors the loop continuously.
Why it matters for your car
Faults prevent the car from starting. Loose connectors can trigger HVIL errors.
Other terms
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