Quite a different issue but this reminded me of a small 98cc Gilera motorcycle that I owned. It was built in the '60s and had no battery. Probably for some sort of safety reason the ignition circuit went to mass (earth) through the brake light switch (normal closed) . This was organised in such a way that when the brake was applied the switch was open so the path to mass was through the brake light bulb. The result of all this was that if the brake light bulb was blown the engine cut out when the brake was applied. It took me a while to understand why the motor cut out every time the brake was applied.

Peter

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