Injector fuse causing ecm fuse to blow when in . With the injector fuse removed the ecm fuse does not blow. I checked the entire harness for shorts !!!! With the injectors unplugged and the injector fuse in, shouldn’t it break the circuit , right ? And not cause it to blow the ecm fuse ? But still does . Is my ecm screwed ? I highly doubt ? 2007 g35x vq35hr. Yes i looked at the FSM , looks like ecm sends power straight to injectors . Getting full 12v at all injectors as well. I ran thru all my other fuses and came to the conclusion that its defiantly the injector fuse causing the engine control fuse to blow . This happened out of the blue as well.

 

Good luck. Electrical problems are a *****

 

You need to unplug the ECM, unplug the injectors, and check for continuity (ohms/resistance) between each wire and ground. Sounds like something IS shorted out (probably melted/grounded or simply broken/grounded) which is causing the fuse to blow due to overcurrent.

Section EC page 456 has a table of the values you're looking for. I suspect you'll find one of the terminal 1 injector harness wires going to ECM pins 81,82, 85, 86, or 89, 90 is shorted out to ground causing the problem. You can find the ECM pinout somewhere in the PG section I THINK near the end. NEITHER OF THE INJECTOR HARNESS WIRES SHOULD BE SHORTED TO GROUND!

How it works basically is terminal 1 on the injector harness delivers a constant 12v from the IPDM (I think, too lazy to look it up right now), pin 2 is the injector pulse from the ECM which is pulsing a GROUND for the injector. The ECM does not pulse voltage out to the injectors the ECM is the ground for the circuit.

 

 

Here's the pin layout of the harness so you can tell which is pin 1 and which is 2. Sounds like something grounded out so start tearing the harness apart until you find it. Factory service manuals are available again so look up your model year and chassis, this stuff is under section EC Engine Controls, look for fuel injection stuff somewhere around page 325 probably.

https://nicoclub.com/archives/infini...e-manuals.html

 

 

F102 is the big ECM harness.

 

 

These are the ones going to the injector, that pink wire goes to the ignition switch.

 

And did you verify that it was an injector harness pin 1 or 2 wires that are going to ground?

 

 

It doesn't matter what color the wire is tbh and it can change depending on the year. What you need to verify is that with the IPDM fuse 44 pulled there is none of the pin1 injector harnesses going to ground, with the ECM unplugged that none of the pin 2 injector harnesses are going to ground.

If it goes to ground then you need to take the wire loom apart and unpeel all the electrical tape off the wiring and find out where it's going to ground. Usually this happens at a point where it goes through the chassis like the grommet in the firewall or the grommet in the battery compartment.

Also make sure the positive battery lug isn't touching the frame since you have it disconnected. Might be giving a false reading because IT is actually touching ground. If you pull IPDM fuse 44 then it won't matter because the circuit is interrupted.

The power layout for that system is in the FSM section PG on page 456.

If you have ANY of the injectors still plugged in you might have a failed injector that blew apart on the inside and is grounded out. Injector resistance across it's two pins should be like 12 ohms.

 

 

Frustrated is not even the word . I have been battling this car since a bought the damn thing . Making me hate the Infiniti brand. It seems no one has any answers or any clue at all. Yes i know what i am doing and ive had a few electrical engineers as well as Nissan techs look at the car as well.

Here is my issue !!! The injector fuse #44 is causing my ECM fuse to blow. I have looked thru the entire wire harness and checked all my grounds . The FSM from infiniti is by far the worst FSM ive seen in my entire life . Extremely horrible to follow. I have disconnected my ECM and my fuel injectors and checked for continuity. At the fuse box , i check the fuse terminals for ground , one side is open , why would one side of a fuse box be grounded ???? Im on Long Island NY , if anyone can help . I WILL PAY !!!!! Two mechanics, Nissan Tech, Electrical Engineers with a PE Degree and no one can figure it out !!!!

 

Ok the next step is to go through all your injectors themselves and measure resistance across the injector pins (not the chassis wiring harness just the unplugged injectors). Each injector should have roughly 12 ohms resistance, if you only have 0 or 1 ohm resistance then the injector probably exploded and is grounded out internally.

If that test passes then remove the IPDM (unplug it from it's harness which is harness number E3 and F1) and see if the short clears up once the IPDM is unplugged.

If the short still exists then you have a problem on the chassis wiring between that harness E3/F1 and the injectors. If the short goes away when you unplug the IPDM then the problem is on the other side of that harness or internal within the IPDM or the BCM circuit.

That fuse also supplies power to the BCM internally within the IPDM, on the IPDM harness pin 19 goes to the BCM but pin 51 goes to the injectors (both soldered to the same end of fuse 44 internally). With the IPDM unplugged you can read resistance on both those pins (with the BCM unplugged) and there should be an open circuit, no short. If there IS a short then the problem lies on the BCM circuit in series with the injector circuit.

If both those measure as open circuits then something probably exploded inside the IPDM and you just need to replace it with another one.

You can see the internally soldered connection in PG-67 and how it splits to both the BCM and the injectors.

Injector resistance values are EC-457