High Voltage Interlock Loop

A small low-voltage loop routed in series through every high-voltage connector, cover and service disconnect on the vehicle. Removing any of them breaks the loop, and the moment it opens the module commands the battery contactors open, isolating the pack from everything downstream. The effect is that you cannot expose a live high-voltage conductor by dismantling something — the act of dismantling is what de-energises it. A car that will not move because this loop is open is a safety system working, not a fault to be worked around. Never bridge or bypass it: doing so removes the only protection between a technician and several hundred volts, and it reports itself as intact whatever is disconnected.

Also known as: hvil, interlock loop, high voltage interlock, safety interlock, hv interlock

Referenced by 15 codes

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Codes involving this component (15)

Other components in Hybrid Propulsion

Information, not instruction

CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.

Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

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