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Quote from: fphil on December 28, 2016, 04:59:56 pmWhat about connecting a resistance to drop this 4V Under the threshold voltage of the relay? Or else you could upper the thereshold with a diode.why just not make relay supply die when ignition is off?
What about connecting a resistance to drop this 4V Under the threshold voltage of the relay? Or else you could upper the thereshold with a diode.
I think your magic trick will be to insert a 18V zener diode.
Bringing this back from the dead - I have the same problem. Where was the zener diode installed to fix this? Ahead of the fused 12v to VEMS? or elsewhere? thanks!
I think your magic trick will be to insert a 18V zener diode. They work in a way, that current will flow in one direction, and no current the other way (like a normal diode works) but when the reverse voltage exceed the zener level (eg. 18V) can current flow in both directions. In your case, where a protection diode potentially make current flow from a relay power back toward the FET, throu a protection diode, and back to a mains somewhere, can a zener allow the spike protection, but stop the reverse current a normal voltages (12-14v).It's a common issue when the design controls the electornics on both the positive and negative side. Even I thougt that I was carefull when I designed the complete loom for my TVR, did I end up with the nice feature that turning on the long beam, with the key out... made the ECU power up..... a couple of hours and a few diodes later, did it work as expected :-)Injector flyback, that is powered from the injector +12V should normally not have power without the ECU is on power, Either by using the same relay for both injector + ignition + ecu power, or by powering the injector and ignition with the fuel pump relayBr Mads