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83 l28et swap harness into 73 240z wiring help!

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Hello, I am about to pick up an 83 l28et, with matching ecu and necessary electronic sensors/components in a few days and have some questions for the wiring gurus about this swap harness I recently purchased. This will be my first engine swap, and the engine will be going in my 73 240z. The harness I have came from a 73 240z running an 83 l28et so I thought everything should be fairly plug and play. But after looking over numerous write-ups on the swap, and going through my harness I found it is missing stuff and is different from the other 83 turbo harnesses I have seen on the forum. For one there isn’t a plug for where the 280zx turbo ignition harness connects to this harness; however I have found wires near where the ecu plugs in where it could have been. Here are some pictures




From left to right - (yellow with white stripe) (solid yellow) (solid yellow merging to a thicker gauge black wire)

Anyone have any idea as to if these went to the ignition harness plug or possibly should go to the ignitor?


Moving right along, on the other side of the harness (180 degrees around) are three more cut wires (only two pictured). They are a black wire with a white stripe, a white wire with yellow stripe, and a solid black wire. Any ideas what these go to/should go to?




A little further down is a cut blue wire with a black stripe. Any ideas what this went to/is for?




Next is an insulated black and red wire both in the large grey insulator. I read somewhere that the black wire was just a ground, can anyone confirm this? I have no idea on the red wire.




Right next to that is a plug with a black grommet and two wires coming from it they are yellow with green stripe, and black. I’m not sure what sensor this is for but I believe it is either the knock sensor or the oil pressure sensor, the plug is similar to the injector clips, but its on the wrong side of the harness. Can anyone confirm what this is?





On the other side of the wiring harness are two connectors I ‘m unsure of what they hook up to, one is similar to the injector clips and the other also similar but has 3 pins. They are slightly up from where the AFM wires branch off.  Any ideas what these go to?




Front view




Slightly further up the harness from those two plugs, is the black wire pictured.  Anyone know where this goes? I’m thinking maybe to the temperature sensor or something.




Alright lastly, on the opposite side of the harness, I have a weird box with three wires coming out of it, they are green, brown, and black. It hooks into the harness near the fuel pump relay and has a constant 12V from the battery post going to it. I haven’t seen this in any of the write-ups and am scratching my head as to what it is and why it’s in the harness. Anybody have a clue?




I know it seems like a lot to ask, but I’m really blanking on some of these. If need be I can supply greater detail on where some of these are located on the wiring harness. Also does anyone know where and what wires I will need to hook the ignition harness to on both the 83 280zx turbo harness and on my 73 240z? Or where the igniter would wire into this harness? I need to know if I should pick up the ignition harness when I get the motor later this week, or if I can just extend some of the cut wires if they are the right ones I’m thinking of. Also is there supposed to be a main efi relay in here somewhere as well as fusible links? Because all I have found is the fuel pump relay, and haven’t seen anything similar to the fusible links posted in the write-ups. Any insight would be greatly appreciated.





Edited by AaronK

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I take it you never got the chance to see a stock zxt engine bay. I have a couple photos on another site. Maybe I find them later. If you hadnt yet, look at the ECCS component diagram, and read what each part does. Then try the wiring diagram. Find part x that plugs in by wires, and next to it is the wire colors. You have access to answers, and I think that is why more responses have not been seen. Anyhow, the 3 terminal connector that is near the injector/AFM could be TPS if you have only 2 wires in it. Two wires to CHTS, by knock sensor. Match things up. Keep lables being written and attached. Eventually it will start to make sense. When you get stuck come back.

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It may have been "plug-and-play" if the previous owner had explained how he tied all that wiring into his '73 harness...  I hope it'll get easier, but from the pics you've posted so far, I'm afraid it'll be harder than it needs to be. 


You'll also probably have to back up a ways and take some new pics with more "context" - most of us aren't going to recognize some of those small snippets of wire ends (because that's NOT how we did the (re)wiring...).  But seeing it with more context (more of the wiring harness in view) someone may see something and say: "OH...  That's what he did with that wire..."


I can tell you about your last picture:  The "WTF is this box" is the Fusable Link Holder from a stock 280ZX.  The Green and Brown wires going into the bottom are the main power sources for the ECCS system (ECU and engine harness).  In it's stock form, this box will have power directly from the battery (and other switched sources) which will go through fusable links (same function as a Fuse) and then on to provide power to various components.  You're obviously interested in the power to the ECCS.  You need power from the battery to "feed" the 2 fusable links that feed the Green and Brown wires...


That should be part of the engine harness that would go across the firewall from the master cylinders location and will also contain wiring for the CHTS (Cylinder Head Temperature Sensor) and the Knock Sensor, plus the EFI Relay (probably - well, maybe) and a white connector (most of this stuff ends up near the battery - it's location in the stock 280ZXT)  It'll really help you to see an actual stock 280ZXT harness layout and make sure you have the Factory Service Manuals for both cars - the '73 and the '83 280ZXT (I find the '82 FSM easier to follow and it has the same info as the '83 FSM)


The wiring to the Coil/Ignitor is in a seperate harness on the stock 280ZXT.  It's not difficult to re-wire if you understand the circuit.  I always found it helpful to have the original coil harness BUT it also contains a lot of other wires that you'll never need or use.  The 280ZX had some other stuff up near the coil that required wiring...  I just unwrap that harness, remove the unneeded wires, and wrap it back up.  What you need in that harness is: Black/White (IGN ON power to the Ignitor and Coil - GND comes from the body (coil bracket bolted to fender well)), Blue (signal to Tach (which I just realized you can't use unless you swap out your early Tach for a '74-'78 Tach)), Yellow/White ("trigger" signal from ECU to Ignitor to tell the coil to fire - this wire ties back to the white plug that comes out of the ECCS harness near the ECU)


Your next-to-the-last picture looks like the wire that goes to the O2 Sensor.  If it is, it'll have a squarish body with a male spade on the harness end.  Take it apart, show us the end.  What's on the end of it right now is hard to recognize.

Edited by cgsheen

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