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Discussion Starter #1 (Edited)
I'm having some trouble figuring out what is required to modify an 05 Engine Control Harness with NATS to an 03 Engine control harness without NATS.

Can anyone point me in the right direction? I've modified all other connections successfully, but was struggling to figure this one out.

I've searched the site, but have only found posts saying it can be done.

@MoltenNismo

Thanks
Gary
 

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Gary, I assume you're trying to run an 05 harness into your car. What have you done so far and what are you trying to figure out?
 

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Discussion Starter #3
Gary, I assume you're trying to run an 05 harness into your car. What have you done so far and what are you trying to figure out?
You are correct. I have everything rewired that needed to change from an 05 to and 03 including changing connectors except for the NATS portion. I'm not sure of how the car is supposed to be wired without NATS. The 05 harness was from a car with NATS. The 03 car that I am putting it in does not have NATS
 

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At the ECU end it doesn't matter if the car has non or nats. The important thing is the ECU that you'll be running if that's non or nats.

Just to be clear, you have an 05 nats harness and you're plugging in a non-nats 04-05 ECU? If so, then swap pins 72 and 61 (cam/crank) and move pin 114 to 113 (fuel pump relay control).

That's all there is to it, unless you are running an 06 ECU which will require you to pin in the AF sensor pigtail. Let me know if you need that too.
 

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Discussion Starter #5
At the ECU end it doesn't matter if the car has non or nats. The important thing is the ECU that you'll be running if that's non or nats.

Just to be clear, you have an 05 nats harness and you're plugging in a non-nats 04-05 ECU? If so, then swap pins 72 and 61 (cam/crank) and move pin 114 to 113 (fuel pump relay control).

That's all there is to it, unless you are running an 06 ECU which will require you to pin in the AF sensor pigtail. Let me know if you need that too.
Thanks Alex. I have a whole new appreciation for what you did with the swap harness! I'm actually using a non NATS 06 ECU with an 05 harness from a car with NATS in an 03 car..lol. following all the changes required me to make a pretty extensive excel spreadsheet to track the changes and buzz it out. I am code less at the moment, but the car wont crank. It immediately blows fuse 20 which from what I can see is related to NATS, the cooling fans, and one other thing I cant remember off hand.

I have been using the FSMs to identify the changes which is difficult since they are written as troubleshooting documents and not build documents
 

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Thanks man. I appreciate the kind words.

As far as it not cranking, that has nothing to do with the NATS or ECU. It should crank even without an ecu. Firing would be different though. If you keep blowing your fuse, that means you have a short. Fuse #20 is also the fuse for the clutch interlock relay. Double check your wiring there.
 

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Discussion Starter #7
Yeah, that sounds like that would be where the issue is! Thanks for the reply
 

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Discussion Starter #8
The black and red wire on the clutch interlock is reading 0 ohms to ground...now to trace it and find the short...
 

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0 ohms or NL? 0 ohms means that there is nothing stopping the current to go to ground which means there is a short. It should be NL or no limit meaning there is a ton of resistance which is what you want.


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Discussion Starter #10
Found my issue. For some reason I hooked up 03 F47 8 G/W wire to the 06 F47 pin 8 B wire which is a ground. I believe the 03 F47 8 G/W wire just needs to be terminated at the connector because VIAS and EVAP get power through the F35 ECU relay now. Do you know what the ground was for on the 06 side? I can't seem to find it in the FSM @moltenismo
 

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Yea as you mentioned if you have power going in to those then you're fine. Pin 8 has continuity to ground? I can't see it either on the FSM. I wish the Nissan FSM actually has pinouts of actual connectors rather than just have you look it through the entire FSM.
 

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Discussion Starter #12
Yea as you mentioned if you have power going in to those then you're fine. Pin 8 has continuity to ground? I can't see it either on the FSM. I wish the Nissan FSM actually has pinouts of actual connectors rather than just have you look it through the entire FSM.
Yeah that pin goes to the grounds on the timing chain cover. I only know this from buzzing it out. There is no mention in the FSM.
I terminated the wire and as expected, the fuse did not blow. I tuned the key just enough to see if it would crank and it did. I removed the supercharger and drivebelt to get at the harness. The plan is to put it back together tomorrow and give it a go.

Thanks for your response!
 

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Discussion Starter #13
Car started right up and is running well. Now to take the harness back out and redress it. I cant wait to stop taking this car apart and putting it back together and just enjoy it!
 
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