Cut cable in relay box

Meal! Looking for the reason why my motor control light does not glow…or rather looking for the place where the previous owner has clamped off I once made the relay/secure box on the driver’s side directly in front of the windshield. After I unscrewed the cover then I found a cut-out thick black cable under it. In the line is a brown and a black vein. Electricity I could neither When the engine is still stationary, measure it on it. But that can also be because you can hardly get there and the contact was not decent. Does anyone have any idea what kind of cable this could be? I took another photo so you know what I’m talking about And where I am here. Where would someone like to jam the engine control ramp?