English to French Other Automotive / Cars & Trucks

Hello,

Mentioned in a non technical text, this relates to a motor bike from what I can guess by the context (or lack of such).
Is it the same as an ignition switch?
That's my guess more or less. As the man hit the wall when his motorbike suddenly stopped for the oil level went down as he was looking at a girl in little clothing on, so did not pay any attention when the drop in oil in the engine turned the "engine switch" off.
I'm not even sure this holds any credibility, but I'm not responsible for the author's fantasy when he describes a dream he had. Dreams by defintion do not care much for feasibility.
Thank you !