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It's not really a problem. If the inertia switch is tripped, the buzzer is connected to the ECM pump output. When the key is turned on, the pump output goes to 12V for 2 seconds before it shuts off. The buzzer will indicate a tripped inertia switch then. If you try cranking, the ECM will turn on the pump output, again sounding the buzzer.
The way he has it hooked up now it seems like the buzzer should be sounding all the time because the ECM isn't outputting 12V with the key off. The buzzer won't sound for the first two seconds after the key is turned on, until the ECM turns the output off. Then the buzzer won't sound while cranking.
This is correct. But I have altered it since...and connected the 12v source to an "12v ignition on" connection point, rather than the "12v battery-always hot" connection point. This way it only sounds once it's been tripped, and stays sounding until i turn the key off.
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Yes is should work that way trying to start the engine, but that is the only time it will turn on the buzzer. And it won't work after the engine shuts off from the inertia switch is all. You would need to try and re-start the engine to see/hear that the switch had tripped out.
Correct. So this brings up a philosophical question about what we're trying to accomplish by including this inertia switch at all. I want a way for the pump to shut off in the event of a hard accident or rollover. In the event that I cannot physically turn the key "off", I want to know that the pump is shut off (because of the buzzer noise...that will confirm it). And that noise and light is a reminder that its shut off, should it "falsely shut off" for any reason. So technically, the ECU stops giving the signal when the engine dies (for any reason), so in an accident or rollover when the engine dies...the pump quits pumping fuel because the ECU signal is not there. And that's fine. But if the accident isn't bad enough to stall the car, and it keeps running, and I'm incapacitated, it want that pump to shut off. Seen too many people burn up in vehicles where they are incapacitated, and it appears fuel is just constantly running out fanning flames.