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Relay back feeding


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I am currently ironing out small issues with a G4 Storm Black installation running a VH45DE+T in a Nissan z32/300zx.  Typical for Nissan of the era, the VH45 V8 has a very similar ECCS ECU and loom to the Z32 This makes the V8 ECU and loom relatively easy to graft into the originally V6  powered Z32 to make it run. This  OEM ECU and loom change has been proven over 2-3 years running without issues prior to the  current change to the Link ECU.

I have made (proven) new injector and coil looms that plug into the transplanted original OEM V8 loom as it passes from the engine bay, through the fire wall etc then grafted a pair of Link short ECU looms onto the end of this in the foot well to make it all work with the Link ECU. There are relays in the  Z32 chassis used that are OEM hot fed so I'm getting the back feeding issues as explained in your Aux wiring help text.

From the wiring diagrams in that help text I understand that a secondary relay is recommended on the high side of the primary relay coil to isolate it and stop back feeding. However because I am using the Z32 chassis wiring as explained above, accessing these loom components and related wiring, like the fuel pump relay for instance, can be much more difficult than for a nice and tidy bespoke Link ECU/relay/fuse set up. Since in my case the Link ECU and approximately 300mm of loom is still easy to access, can I put in the anti back feeding relays onto the  more easily accessible AUX output side of the circuit, instead of the OEM relay coils in each case? Activating/deactivating these should be relatively straight forward using a suitable GP Aux/DI input?

Anyone been here or can you see any issues I can't...



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What you can do is use a relay to switch the ground side of the main relay.

So have pin 45 (12v key) supply 12V to the relay coil to turn it on.

The relay then switches ground to pin 16 to activate the main relay. 

Once main relay turns on it will feed the ECU via pins 49 and 59 

(all pins are the 300Z stock ECU pin numbers)



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