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Link G4+ and Nissan ECCS relay

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Probably not related to the wiring courses (and ive only done efi tuning courses) but still wiring specific. I have recently installed a link G4+ into my R32 GTR and i have a problem that seems to be fairly common on these cars. Basically the ecu cant stay powered on during cranking due to a pretty decent voltage drop. Anyway i am thinking of splicing into ecu pin 45 (ignition barrel signal) and using it to trigger a relay to send 12v+ directly from the battery to pins 49 & 59 (ecu power supply). I have little knowledge on wiring and am a bit scared to do this unless given the green light by someone with some experience in this area. Just want to know if this would be the right thing to do as I have tested the power feed to the eccs relay and it seems to be bang on battery voltage prior to cranking. Also if this is the way to go what rating relay and fuse would be suitable?

Cheers guys.

Are you using a G4+ PNP box or one of the other G4+ models?

Sorry forgot to mention, PnP

Are you getting voltage drop or large fluctuations on the IGSW circuit (45) when cranking?

The Link uses the IGSW circuit as an input to then lowside drive the ECCS relay, which feeds pins 49 and 59.

If the IGSW circuit is sporadic at the start position, then the Link will be cycling the ECCS relay on and off.

I will have to check pin 45 again but the ECCS relay does click rapidly when attempting to crank the starter motor

The common problem is low voltage on pin 45. That pin on R32's is connected to a horrible circuit. It comes directly from the ignition switch and powers many high current devices such as fuel pump, oxy probes, idle valve etc (i.e. no relay,20odd amps going through the ign switch). When the ignition switch contacts get tired you can get a lot of voltage drop on that wire. The Mosfet that controls pin 16 will drop out if pin 45 drops below about 7.5V during cranking. Often moving the fuel pump to a relay is a good fix.

Okay thanks mate, that sounds like an easy enough fix and probably also give my fuel pump a bit more voltage/flow im guessing

In the wiring diagram it shows a fuel pump relay and i see what you mean by the ignition barrel sending power straight to it and the fuel pump. Would this factory relay be suitable to rewire with a direct battery positive feed and use pin 45 on the ecu as the trigger signal?

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