Technical > Wiring & Sensors
Fuel pump relay staying on when VEMS powered OFF through P259 output
fphil:
yes, it dépends on how things can be wired
Wolf_Tm:
--- Quote from: Kamuto on December 28, 2016, 05:34:12 pm ---
--- Quote from: fphil on December 28, 2016, 04:59:56 pm ---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.
--- End quote ---
why just not make relay supply die when ignition is off? :)
--- End quote ---
I already tried to install a 2nd relay (activated by the Main Relay) on the Fuel Pump relay Positive, but even the 2nd one just gets activated by the Flyback!
And if I move the 2nd relay activation wire from the Main Relay to another switched source, then the engine will not start because during cranking the relay will get off.
smurfinator:
--- Quote from: Kamuto on December 28, 2016, 05:34:12 pm ---
--- Quote from: fphil on December 28, 2016, 04:59:56 pm ---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.
--- End quote ---
why just not make relay supply die when ignition is off? :)
--- End quote ---
This is what I did on my 3.6 board since having problems of this nature with my (um...fried) 3.3 board. Nothing in the car gets power until the main OEM power bus relay is switched on by the key. So, there are cascading relays in order to get power: Turn key > main OEM power bus relay ON > VEMS unit power relay ON > fuel pump relay ON. Fuel pump relay is in the boot with its fuse and not on the main (aftermarket) fuse panel, so the pump draws straight from close proximity of the battery with its own heavy cable and chassis ground when the relay is ON and only when all the other stuff is on. So, if I blow the 1 amp VEMS fuse, fuel pump turns off.
Wolf_Tm:
--- Quote from: Mads Lund on December 27, 2016, 11:47:52 pm ---I think your magic trick will be to insert a 18V zener diode.
--- End quote ---
And it was! It worked wonderfully, thanks!!!
grillage:
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!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version