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wam8827

280z Harness Help (Plug/Wire Identification)

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So I acquired a 76 280z with the stock drive train. It was missing the fuel injection system (Intake Manifold, MAF, and etc). I bought a donor motor/trans, that came with full harness, maf, ignition coil, transistor module, and basically everything I needed.

Got most of everything installed but having some issues with some wire/plug identification. I've searched and looked at so many damn wire diagrams and for the life of me I can't figure out which plug/wires these are. So any help would be greatly appreciated! The stock drive train won't be in for long, but I'd surely like to get it back on the road running on its own power!

Edit: won't let me upload pic from mobile. Will post pic from laptop when I get to the house. But the plug is a 3 prong (green/yellow, yellow/white, and black and yellow. The connector it was to had 3 wires also (yellow, white, and red; this wire had a bullet point connector on it)

 

Edit: pics!

 

 

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Edited by wam8827

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Kind of looks like the test port for the BCDD.  Check Emissions chapter.  Also shown in the wiring diagram right across from the Air Flow Meter (AFM).  These cars don't have a MAF sensor.  The MAFS can be called an AFM, but not vice versa.  

 

The diagram shows more wires because they show all versions - California, Federal, Auto, Manual.

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Would've never thought to look in emissions, I appreciate the lead! I will have more questions and pics for which I'm having issues with. I don't know why, for the love of god why the PO would take out the efi and go to a carb setup. I was told the PO said the efi felt gunked up and wasn't working correctly, so he ripped out all efi and went to a more expensive carb setup and then it didn't even run that great so he ended up selling all of it.

 

So I'm working with a half cut/tore apart harness that I'm trying to piece back together while trying to figure everything out. I'll check out the emissions and etc, and report back in a few days with the other questions I have. Thanks again!

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I think you need to back up a bit with that first pic.  I think we need more context.  The Black/Blue and Black/Yellow in the area of the coil usually go to the ballast resistor. (Both are a feed from the ignition switch - Black/Yellow is always "start signal" on these Datsun's)  So...  Better picture and download the Factory Service Manual.  Studying the Ignition system will help I think.

Edited by cgsheen

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That plug doesn't have any blue. It'd black/yellow, green/yellow, and white/yellow. The blue wire you see is coming off another part of the harness. I will snap better pics later today to be more clear.

 

As for the FSM, I've read over and over for this type of plug with the wires, didn't see anything... Unless I'm just blind?

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As for the FSM, I've read over and over for this type of plug with the wires, didn't see anything... Unless I'm just blind?

Show the plug side of the plug, not the wire side.  And FSM means Factory Service Manual, you're not using Chilton or Haynes are you?  Get Factory, Open Emissions chapter, go to BCDD section.

 

I said "kind of" because you didn't show the telling part.  That port is right next to the coil and distributor wire connection block.  It's an odd one and looks like it should have a counter part connector.  But it doesn't, unless Nissan has a machine that automatically tests.  Maybe they do it during assembly.

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Well had a little bit of progression with the Z. I'll have to update you with pics and some other wires I can't seem to locate. Got the Z running, but she's running real choppy at the moment. Put in a new fuel pump, hardwired it to the battery with a switch for now it kept wanting to start but just wouldn't give. Held the AFM flap open with an extension and she started up, but real real sloppy. 

 

Finally unplugged 2 sets of wires, and boom she started idling what seemed pretty steady. Under throttle load it had quite the hesitation though. Plugged the wires I un-hooked back in and she died. Needless to say it will start up, idle and rev to 2k before the hesitation starts and the AFM starts popping and sputtering. Will snap some pics tomorrow morning of whats going on.

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There are several different Coolant temperature switches on these things. The one wire bullet connector ( White or yellow) is for the dash gauge.

 

Then there is the two pin " Engine " Coolant Temperature switch which sends the engine water temperature to the ECU. This switch affects running and driveability more than just about any other sensor. It has two wire leads that are black in color. These wires have bullet connectors that plug into the engine harness to two wires that are also Black in color.

 

Then there is the Thermo-time switch, it controls the " Cold start Valve ". It also has two Black wires that terminate with Bullet connectors. It plugs into the engine harness side with two Dark Green wires. But here's the neat part. After years of grime and dirt accumulating, the two Dark Green wires magically change to Black!!! Guess what happens if you mix the connections up between the Engine Coolant Temperature Switch and the Thermo-time switch? Yes it runs like a bag of S**T. You have to wipe the oily gunk off if Brake Cleaner to sometimes find the true color of the wires.

 

Here is a picture of the Different wires. Click to enlarge.

 

bullets.jpg

 

 

 

On Federal models, the distributor has two pickup coils inside. One set is advanced and one is retarded. They are controlled by Water temperature and yes, there is a separate Water temperature switch for this as well.  Fortunately this switch is a bit different than the other. Has two wires attached, but one has a ground " Ringlet " on it and bolts to the thermostat housing. The other wire ( Black again ) terminates in a Bullet connector. This is a single wire though and it connect on the engine Harness side to another BLACK wire . Fortunately the engine harness wire has a Red band around it to identify it. Only some years of Federal models have the dual pickup system. California models only have a single pickup in the Dizzy.

Edited by Chickenman

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Note that all of these connections are very sensitive to corrosion. You'd be well advised to get yourself a spray can of De-Oxit to clean all electrical connections. Corrosion on the pins of the Engine Coolant Temperature sensor will greatly affect the running of the car.

 

Note: On a car this old, corroded electrical terminals are everywhere. Back in the 70's they did not have weather-pack connectors like modern cars. Start methodically taking apart ALL electrical connectors and meticulously clean each one. De-Oxit, some fine sandpaper and a small flat blade screwdriver for scraping hard corrosion off pins, are all required tools on these things. Once the connections are properly cleaned, apply Dielectric grease to keep out moisture.  Clean and tight electrical connections make a world of difference in how these cars run.

 

Here is a picture of all of the water switches, including the extra one on the side of the Thermostat Housing for the two pickup Federal dizzy's.

 

Click to enlarge:

 

compon1.gif

Edited by Chickenman

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Finally unplugged 2 sets of wires, .............................. Plugged the wires I un-hooked back in and she died. 

Why guess when you don't have to?  All you need is a meter.  Maybe even just a test light.

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Well I forgot to snap some pics earlier today, but I did some looking of the wires, terminals and etc from the responded posts! They did help quite a bit, but when I went looking through the harness it seems that a lot of the harness seems newer and redone. However I did find out that my TPS sensor is temperamental and probably bad.

 

I unhooked all of the coolant sensor wires, the cold start injector, and the other plug that's pretty much underneath the CSinjector. Also unplugged the TPS and boy did she run a hell of a lot better. Actually made it around a few blocks and got got above 45mph on the little stretch of open road. My ultimate goal is to get this running decent enough so I can drive it where I need to for the remaining of body work and etc. If I didn't care about the body work, I'd just start ripping everything out for my 2J swap.

 

Thanks again for the replies and help! 

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 my TPS sensor is temperamental and probably bad.

 

I unhooked all of the coolant sensor wires, the cold start injector, and the other plug that's pretty much underneath the CSinjector. Also unplugged the TPS and boy did she run a hell of a lot better. Actually made it around a few blocks and got got above 45mph on the little stretch of open road. My ultimate goal is to get this running decent enough so I can drive it where I need to for the remaining of body work and etc. 

Open that FSM chapter.  It's not as hard as it looks, it really isn't.  You're just hacking around until you do.

 

Y'all people are every where.  Hack, hack, hacking away - http://forums.hybridz.org/topic/125532-wont-start-after-fuel-rail-upgrade/?do=findComment&comment=1173508

 

http://www.nicoclub.com/FSM/280z/

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Well finally got some free time to post what I've got going on. So finally got the Z running and driving under it's own power. Discovered timing on the pump shaft was off quite a bit. So got it re-timed now it's running/driving pretty good. However it's running extremely rich. Discovered the AFM I had from the Z was previously messed with on the adjustments. Ended up finding a AFM from a 91 Corolla that bolted in, and the connector plugged in perfect. It seemed to run a bit better after installing this AFM and help with the richness. I've primed the fuel supply/return line and got so much crud and nasty fuel that came out. Changed out the fuel filter, changed oil cause it looked and smelled like it was half gas.

 

Still in the process of working out the kinks. Replaced the plugs since they were unreal fouled from how rich it was running. Tested the coolant temp sensor, ended up being bad so I replaced that as well. Tried the 1k linear pot fix that I found on atlanticz, still no fix. If you get on it pretty hard you can literally see the fuel gauge drop, it's pretty crazy haha.

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