Momentary relay for a switched circuit

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The first one at the link below may work for you. The relay is standard relay that you can get at a auto parts store and the other parts you can get at radio shack. The bigger the cap the longer the momentary signal. Just be aware that the capacitor is polarity senstive and if conected backwards will fail (could explode) (Silver end is neg and the insulated end is positive) There will be a diagram on the side with a - (neg) symbol on the side that points to the negative (ground) end also.
Special Applications with SPDT Relays, Diagrams
I built this yesterday and will be using a part #272-1022 so that i can have a momentary signal for about a second or so.
I just installed a viper 5901 alarm/remote start in my vehicle. The alarm has a feature to turn on the rear defroster when the temp is below 55 degrees and I'll be using this same signal to send a momentary low (ground) to the seat heaters so that they will automatically turn on. Hope this helps...
Another thing to keep in mind is that for this circuit to be able to activate again it will need to lose power so that the cap is able to drain.
 
Monsterx7, I didnt look up the part numbers you posted, but more than likely it's a fuel pump relay. When the key goes to "on" It sends signal to the fuel pump relay. The pump runs from 3 to 5 seconds to pressurize the injectors for the start up, then goes off. After the start, it comes back on and stays on till the power is cut, or the impact switch is tripped.
 
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