Damaged high voltage cable insulation

The insulation on one of the orange high-voltage cables has been breached — chafed through, crushed, cut, or degraded by heat.

This is not the same fault as a damaged low-voltage wire, and the difference is the whole reason it has its own entry. A breached signal wire gives a wrong reading. A breached high-voltage cable gives a path from several hundred volts to something a person can touch, and the property the car monitors continuously — isolation between the pack and the vehicle body — is exactly what it destroys.

So the vehicle's response is deliberately unforgiving. Isolation faults tend to open the contactors and refuse to operate, rather than warning and continuing. That is correct behaviour and should not be worked around.

Where it happens is predictable, which helps. These cables are thick and stiff, so they are damaged where they are constrained rather than where they are long: at bulkhead grommets, where they cross the subframe, at the points they are clipped, and anywhere a previous repair has left a clip off and allowed the run to move. Rodents chew them, jacking in the wrong place crushes them, and underfloor runs meet road debris.

Two properties make it hard to catch and worth knowing about. Damage that has not yet reached the conductor causes nothing at all until moisture arrives — so the fault appears in the rain and clears when dry, which reads as a phantom. And an insulation tester will find in a minute what a visual inspection can miss entirely, because the breach may be on the underside of a cable inside a loom. Nothing about this is a home inspection: the hazard is electrocution rather than shock.