Pac_Man Posted December 1, 2014 Share Posted December 1, 2014 (edited) Well, I figured it would happen eventually. I'm trying to figure out the wiring before I get the engine in the car so the swap goes as quickly as possible. I've gone over the sticky as well as the more extensive and hidden version of the same thing. Harness is from an 82/83 280ZXT and going into a '76 280Z The diagrams and pictures I've seen have two plugs near the rubber firewall grommet, one for ignition (8 wire plug) and one for the fuel pump/fuel pump relay (6 wire plug). However, my harness has two 8 wire plugs, and the wires and colors do not match those of the diagrams I've seen. It doesn't even match the '83 FSM diagram. The person I bought the harness from labeled a couple wires in what seems to be the fuel pump and fuel pump relay plug harness, but I can't verify them obviously since the plugs and wire colors don't match what I've seen. Diagram that has been referenced: I'm also confused on the two wires that feed power to the EFI relay. They were connected to fusible links, but the sticky says stick them on the POS terminal of the starter. Shouldn't they be fed power after fuses? I'd assume I can hook them up to my fuses that are currently in the car (I did the maxifuse swap) but I'm not sure... Also, I'm unsure about where to wire the power wires that are in the EFI relay loom. 1 constant 12v and 2 switched 12v. If anyone has done this swap and would like to guide me on where would be a good spot to do this please let me know. Maybe I'm just thinking about this too much but I keep second guessing myself and running into weird issues like the plugs and wire colors not matching. Pictures attached show the plugs in question. Edited December 1, 2014 by Pac_Man Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 2, 2014 Share Posted December 2, 2014 (edited) Power - The 2 wires (Green, Brown) that supply power to the ECCS are normally connected to the Battery through fusable links. Your last picture shows the Green & Brown and their stock white connector. On the ZX, that plugs straight into the fusable link. So, you can cut off the connector (or find a mating connector with wires) and run the G and Br to your fuses. Battery(+) -> Fusable Link -> Green Battery(+) -> Fusable Link -> Brown You can use your maxi-fuse(s) in place of the fusable link(s). (I don't because it confuses me. I just grab the fusable links from the 280ZX. The fusable link is a wire size smaller than the wiring it protects (the thought being: it'll melt before the "protected" wiring does...) I don't think I've ever seen a definative "this is the amperage FUSE you need in this circuit" to replace the fusable links. I know there have been some guesses and some "this is what I used and I haven't had a problem" but I don't know if anyone has studied the amp draw...) Black/White in early Nissan/Datsun's is always "Battery Voltage at IGN ON" . - It originates at the IGN Switch. - There are a few components in the ECCS and/or Coil/Ignitor that need a B/W connection. - All Z Cars have a B/W to the coil area in the stock harness. EDIT: The second 8-pin connector you have in the pictures is for the Fuel Pump Modulator. It shouldn't be cut apart and it can be left UNUSED. If you install the modulator box, you'll need to do additional wiring to the fuel pump. My advice - don't use it... The Blue/Black does NOT provide power to the fuel pump. Wrap everything up so there's no chance of a short. The wire marked "Fuel Pump" in the picture above would normally be a Blue/Red (L/R) AND it would connect to Pin 16 on the ECU (and the ECU socket...) Trace that wire to the socket and see if it's correct. - It is used to set the fuel pump relay (turns the relay on and off) - - It provides power (battery voltage) to one side of the relay coil. The other side of the relay coil is GND. - The stock Fuel Pump itself is wired like this: Battery -> Fuse -> Fuel Pump Relay -> Fuel Pump The other 6-pin "interface" connector you need is on the part of the harness that runs across the firewall to the battery area (with the power wiring, CHTS connector, knock sensor wiring, etc.) That's the connector that'll have the L/R to the fuel pump relay coil, B/W for the IGN ON power, and Y for the temp gauge... Edited December 2, 2014 by cgsheen Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted December 3, 2014 Author Share Posted December 3, 2014 Thanks again sheen. I do have the fusible links but I figured I'd just hook them into my updated wiring since, well, why not. I don't have the fuel pump relay though. I was thinking that to keep things simple I'd keep the fuel pump wired as it is stock in my car. So to connect the temperature gauge do I need to splice mine into the Y wire on that 6 pin connector you're talking about? And any B/W wire needs to recieve switched 12v? Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 3, 2014 Share Posted December 3, 2014 The 6-pin and 8-pin connectors are "interfaces" with the other harnesses in the ZX. Otherwise the ECCS (engine) harness is pretty self-contained. Some of the "interface wiring" won't be used - they're either for items not present in the early Z, or they're things you won't care about anyway... The important stuff is in that drawing you posted above. Temperature Gauge: You have 2 options... 1. Use the existing wiring, connect it to the new engine's temp sender. If your stock harness is still in place (wiring that came across the core support to the coil and etc.) there will be a Yellow that connected the sender to the gauge on your original engine. Just hook it back up. 2. The ZX put the gauge wiring in the ECCS harness - it was easier to run it that way. SO, they needed to bring that back to the body harness. You can use that Y and tie it back to your gauge wiring at the firewall or under the dash or something. Option #1 is easier if the stock wiring is still there. If you do, just ignore both ends of the Y temp sender wire in the turbo harness. You do need the B/W connected to the other B/W's in your car. There are engine components that need the connection. The Turbo fuel pump relay is the simplest relay possible. The fuel pump relay in the '76 Z is part of the overly-complex EFI relay. If you can figure that out, more power to you... Me, I just use the ZX relay and run the output to the Green power wire for the fuel pump. You'll find it under the glove box (and the harness that runs down to the floor on the right side - running to the back of the car.). You REALLY want the ECU to control the fuel pump so my advise is to ALWAYS wire it up like it's wired in the ZX... Safety first. Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted December 3, 2014 Author Share Posted December 3, 2014 Ok, I'm going to go with option 1 for the temperature gauge. I've got the ignition wires traced and labeled. Labeled the fuel pump modulator connector just so I'm never unsure about what it is or if I need it. Just did some wire tracing and diagram checking. My fuel pump relay wiring ends at the female connector on the harness. No relay or connector for it. Can I get some kind of generic relay? If my understanding is correct, I would need one that has switched 12v to turn on, ground, 12v out to the fuel pump, constant 12v, and then the connection to the blue/red (L/R) wire that goes to the ECU. Now my only question is, what is the function of the connection to the ECU? Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 3, 2014 Share Posted December 3, 2014 The stock 280ZXT fuel pump relay is a simple single switch relay. It takes four conections: 1. "Source" voltage to one side of the switch. - - - On the stock '76 280Z: Battery -> Fusable Link -> main power to IGN Switch (tee off this wire for source power to fuel pump relay) 2. "Output" power to Fuel Pump on other side of the switch. Relay -> Green wire to Fuel Pump 3. GND to one side of the relay coil. 4. Blue/Red from ECU to other side of the relay coil. The way this simple relay works, it does matter which side of the "switch" is wired to "source" and which is wired to "output" and the same holds true with the coil - as long as one side is GND and the other is the "control" wire from the ECU. The ECU controls the relay with the L/R wire. So it "turns on" and "turns off" the fuel pump using the relay. The ECU controls the fuel pump for safety. It knows when the engine is turning (C.A.S. signal) and will kill power to the fuel pump when it's not turning. In a collision, ("we don't call them "accidents" anymore" - Hot Fuzz) it keeps the fuel pump from running on and possibly spewing fuel where you don't want to be spewing it... A relay is just an "electric" switch. It "makes" or "breaks" a circuit. The simplest example is having two wires in your hand - touch them together and the circuit is "complete" or "made", remove them from each other and the circuit is broken. The relay has a "coil" which is an electro-magnet. When it is powered, it pulls a bar down that connects two wires together (that's the "switch"). When it is unpowered, it releases the bar and the connection is broken. Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted December 3, 2014 Author Share Posted December 3, 2014 So could I just use a generic relay like this? Then I would wire it like so?:30: 12v constant 87: to fuel pump +86: ECU signal wire 85: Ground Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 5, 2014 Share Posted December 5, 2014 Yup. Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted December 5, 2014 Author Share Posted December 5, 2014 Wow, maybe I am learning! Thanks for all the help, I have the whole harness labeled now and a much better grasp on how the whole ZX system and wiring works. Quote Link to comment Share on other sites More sharing options...
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