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Back Feeding Power Issue


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Evening all.

Before i start, i know what the issue is and the corrective action. This is a question so i know the why.

G4+ Xtreme - I am at power up and testing stage; When the ignition is turned to off the injectors start pulsing like crazy, creating a back feed into the ECU.

The reason for this is i have wired the injectors to constant 12V rather than switched. I did this without really thinking about it too much as the factory setup has the injectors wired to constant 12V so i replicated it.

I'm well aware of not wiring solenoids etc to constant 12V driven off normal outputs as that will create a back feed, however i thought the injector drives would have been different having no fly back circuit.

I couldn't really find a lot of information on injector wiring in the help files about feedback on the injector drives other than it stating a switched supply must be used for the injectors (hindsight).

Is this a prominent known issue with having injectors permanently connected to 12V?

Obviously the easy fix is a simple relay install which i shall do.


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No problem, thought that might be the case. I shall install a relay as i knew i'd have to do after turning the key off for the first time.

Maybe something good to add into the help files of the new PC Link release? 

"A switched (key ON) 12V  must be supplied to the other terminal of the injector" is what it currently states. Maybe add in a bit more information;

"A switched (key ON) 12V  must be supplied to the other terminal of the injector to prevent a back feed into the ECU. If the injectors are wired to 12V constant the ECU will stay powered up when the ignition is turned off. This applies to the Xtreme, Fury and Thunder which have peak and hold injection drivers."


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  • 9 months later...

To diagnose I would try removing one aux wire at a time to see which one is causing the issue.  It is easy to pull the pins out of the connector.

It is only the proper "aux outputs" that can back feed on the Monsoon, so injector and ignition drives dont need to be considered.

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13 hours ago, AlexSavv said:

My ecu only seems to back feed if i let it prime the fuel pump... if it doesn't finish priming the fuel pump, it doesn't back feed... any ideas?

I solved mine quite easily, followed the wiring instructions and made sure there were no constant hots actually as relay triggers, only ignition switched live.


Add an ignition triggered relay to your injector power circuit, and in fact all circuits, don’t bother with constant hot if you don’t have to!

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