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TL;DR - Doing a Patch Harness for a Thunder ECU to a 3Plug Evo8MR. Wanting some clarification on parts of the project and some of the translation between the existing Plugin ECU and the Thunder. So I am going to be asking a lot of questions here... Some of them probably deserve their own threads but the list has got too long to split it all up. For this reason, if anyone can comment on any specific part of this post and not the other please feel free to do so and do not feel like you have to answer the whole thing. Also no posting "take it to a shop". This is my hobby so I do enjoy it and don’t mind the time investment. For some background, I have an Evo8 MR which I have installed a G4+ Plugin unit into and tuned myself. It is running great and the whole experience with the software and hardware has been great. With the knowledge in mind of what I plan to do with the car at a later date, I have also since purchased a G4+ Thunder which I am a fairly long way down the rabbit hole of creating and installing via a Patch Harness to connect it to the existing ECU loom plus a Deutsch HD30 bulkhead plug to handle the extra bits. Fun times! However, I am at the stage where I have finished accumulating most of my parts and wire. The majority of my questions have come about from my time spent developing the wiring diagram for this to all work. My wiring diagram has been based of the cross-referencing of dozens of documents, including the thunder diagrams, pinout guides for the G4+ plugin, along with a couple of community created diagrams which I confirmed via the actual electrical manual. Between your G4+ pinout guide and these diagrams, I can see that there are a number of seemingly important pins which you guys do not reference in your pinout diagrams. Some of these are evidently omitted because they dont "appear" within the ECU and thus nobody would need to test or manage them (ie. 5v ground, 12v backup wires). But there is a small clump of others which have no reference or explanation that I would love to get some information on if there is anyone holding such knowledge. The one thing I am hoping is not the case is that the information is omitted because its be controlled 'behind the scenes' and/or proprietary because I will have no way of duplicating the function on the Thunder unit. Thus shooting my "if the plugin can do it, surely this monster can!?" theory right out the window... Furthermore for those of you playing at home, I have a JDM 3plug ECU harness just so you know what diagrams I am looking at. And with that we have the pinout list and the actual questions: Pin 5 - Secondary Air Control Solenoid Valve (Not here to get flamed about still having this installed) - No reference anywhere in pinouts - has a listed pin function of Aux - Ignition 6 - Cant find where it is used/activated on the basemap!?!? Pin 16 - Purge Control Solenoid Valve. This one is referenced on Pin Function Aux Ign 6, but is referenced as Pin 4 on the Pinouts sheet?! I cant find a single wiring diagram that says its located on Pin 4. Again, this isn't referenced by any controls or tables on the basemap. Pin 8 and 52 - These refer to 'Alternator G' and 'Alternator FR' respectively - No reference anywhere in Pinouts OR pin functions. Could not really find much other than speculation about what it did online either. Would love some definitive info here. I would also appreciate some guidance on how to handle main relay wiring using this patch harness technique. My understanding is that the Thunder has its own "Main Relay" so I will need to somehow trigger the existing one. If I can get some tips on how to go about that it would be great! This is one of those things I wouldn't go 'guessing' with as it could blow/melt things if I get it wrong. Will involve a lot of extra reading if someone cant answer this one for me... If anyone can clarify on any of these points it would be awesome - but I am also looking for any overlooked road blocks with this transplant if anyone can flag them. I never really imagined that the Thunder wouldn't work when the Plugin would, but finding these few things that are under the radar, I am asking the question first before I get any deeper. Thanks in advance!