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I have a 1976 280z and I bought the car with a '82-'83 zxt engine installed in it. All wiring was taken from the zxt. I wired everything up to the swap guide I found on here. I think I have everything correct. After all the wiring, hooked up the battery terminals and after a second or two the fusible links started sparking. I unplugged the battery terminals immediately. I thought it could be the alternator so I unplugged the wires to the alternator, but still same problem. I then took a volt meter to the engine block and valve cover with the positive terminal connected to the starter and I got 12 volts on the block and everywhere else that needs to be ground. Except for the chassis. It had 0 volts. I haven't had a chance to go through all of the wiring so I was wondering if anyone could help give an idea to what it could be. Thanks

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 after a second or two the fusible links started sparking. 

 

 I then took a volt meter to the engine block and valve cover with the positive terminal connected to the starter and I got 12 volts on the block and everywhere else that needs to be ground. Except for the chassis. It had 0 volts.

The fusible links would normally just melt, with a touch of smoke, maybe, if there was a short.  So the sparking doesn't really make sense.

 

The 12 volt reading is correct, as you described it, to the block.  What you mean by "chassis" is unclear.  In short, it's not clear what the problem is, besides some sparking.

 

Not sure what you mean by "it".

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Sorry I wasn't technical about the words and misuse of words but yes the fusible link "melted". Not completely melted but it started smoking and the links smell burnt. The spark came from when I attatched the battery terminals. I'm sure there's a short somewhere but I don't know where as some of the wires were already spliced into when I bought the car.

 

 

Ok so the block where the negative terminal bolts down to(the top starter bolt) is suppose to read 12 volts when I have the positive terminal to the starter solenoid? That doesn't sound right. But correct me if I'm wrong.

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I have a 1976 280z and I bought the car with a '82-'83 zxt engine installed in it. All wiring was taken from the zxt. I wired everything up to the swap guide I found on here. I think I have everything correct. After all the wiring, hooked up the battery terminals and after a second or two the fusible links started sparking. I unplugged the battery terminals immediately. I thought it could be the alternator so I unplugged the wires to the alternator, but still same problem. I then took a volt meter to the engine block and valve cover with the positive terminal connected to the starter and I got 12 volts on the block and everywhere else that needs to be ground. Except for the chassis. It had 0 volts. I haven't had a chance to go through all of the wiring so I was wondering if anyone could help give an idea to what it could be. Thanks

 

Fusible Links: You have wired in  a dead short.  Stop and recheck your wiring.

 

Did you install a ground cable from the engine to the chassis?  Otherwise electricity will use things like fuel lines or shifter cables to complete the  ground path.

 

Use the same size cable as for the battery for engine to chassis ground.

 

Might want to consider getting some help.  Nothing worse than burning up an electrical harness.

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Could also be that you connected your battery backward the first time.  It's pretty common.  Once the fusible links melt they don't conduct anymore.  And you might have melted your ground circuits the first time.  You can use your meter to confirm that things are right before replacing them.  Check that you have continuity where it should be before connecting any power.  You shouldn't use smoke as a troubleshooting tool.

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Miles:

 

I might have done so. I'll need to recheck my starter wiring and any other wiring I did and the previous owner had done.

 

No I didn't ground the chassis to the engine. I just put the negative battery cable to the starter bolt on the transmission housing.

 

Ok I'll do that but I'll have to figure out why the engine is getting 12 volts when the positive cable is attached to the starter solenoid.

 

Yeah I do need help with the wiring but I don't know anyone who is good at wiring and troubleshooting. I'm not going to connect both battery cables until I stop getting 12 volts to the engine block where it's suppose to be grounded.

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Disconnecting the alternator was a good idea.  Isolate the various components.  Don't overlook that the electrical system is centered at the starter lug mainly for convenience.  The white wire from the alternator that runs through the fusible links could be connected directly to the battery positive, for example.  You might have a shorted starter.  Realize that the end of that white wire is branched to several subsystems on the way to the end of the battery positive cable at the starter.

 

As you isolate each component, like the starter and/or alternator, and study the fusible link wiring, you'll probably figure out where the short has to be.  Consider completely disconnecting your transplanted EFI system, to be sure that the basic wiring is correct.  Then add the ZX EFI sub-harness.  You might have just switched a wire on the 76 harness by accident.  Confirm that the original parts are still correct.

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You do realize that with automotive wiring the entire car is the ground (neg). So if you put the red (+) meter probe on the plus battery terminal and touch any metal surface on the car with the black (-) probe the meter will show 12v. With a few exceptions each device on the car such as lights or the starter motor have one power wire which when energized electrons pass  through the device to ground because the device is bolted to the body (-) thereby completing the circuit.  Checking voltage from the battery to various parts of the engine doesn't tell you anything.

 

Body/Chassis Ground: Run a black battery cable from the battery to a substantial bolt on the engine and from that same bolt run another black battery cable to the frame/body of the car and bolt it to the frame/body. This will give a ground path from the battery to the engine to the frame/body. Now when you touch the plus terminal on the battery with the red (+) meter probe and the black (-) probe to any spot on the body you will get 12v.  NOTE: all ground cables must be the same gauge (diameter) as the red battery cable that connects the battery to the starter. An undersized cable will melt.

 

 

post-178-0-68028500-1481004637_thumb.jpg

Edited by Miles

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NewZed:

 

Yeah I did a little research after that electrical issue and read that the alternator could be possibly grounded. So I disconnected everything on it to see if that was the issue but it wasn't. I noticed that my starter solenoid starts to rotate when I tighten down the bolt. Not sure if that may cause a short in the starter solenoid.

 

The stock '76 electrical system is no longer in the car. It has the complete harness(efi harness, dash harness, etc.) from the '82-'83 zxt. The interior is stripped out. I will have to take photos of my wiring this weekend when I have a chance to work on the car in daylight so you guys can have a better idea of what I may be doing wrong

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Miles:

 

I understand that the entire car is ground that's why I am wondering why I'm getting 12 volts when touching the probe to the engine block and valve cover when it's suppose to be ground. So this is how I tested with the meter. I bolted the positive cable from positive battery cable to the stater solenoid. I left the negative cable unbolted because I will melt wires with it connected. I touched the black(-) probe to the negative terminal on the battery, and then touched the red positive(+) probe to the starter solonoid bolt and got 12 volts. I then touched the positive red probe to the engine block, transmission housing, and valve cover and got a reading of 12 volts. I didn't hook up a ground cable to the chassis so I got zero volts when I touched the positive red probe to the chassis. So I don't think I'm suppose to be getting 12 volts reading on the engine and transmission.

 

I will try to take photos this weekend when I have a chance to work on the car. And yes the battery and ground cables are all the same size. Thanks for the photo. What would really help us a photo of how the starter wires are attached and how the fusible links are attached because I'm going by the '83zxt swap guide I found here on this site and they said I won't be using 3 of the larger wires going to/from the fusible links, and to cut them and tape them off.

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This is the swap guide I used...I have the '82-'83 swap so I went by one of the other member's wiring on the second page of the write up. I don't understand how the fusible links work in the write up because the 2 wires that go to the starter just seem like it's a loop from the solenoid back to the solenoid.

 

http://forums.hybridz.org/topic/34469-a-quick-fi-and-ignition-280zxt-to-s30-turbo-swap-guide/

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Best advice at this point is that you will need to gather together schematics and the Factory Service Manuals for the 280ZX and your 280Z and start from scratch. Study the documents until you understand the function of each wire. Make a wire list showing color and function and check it against what you have installed on your car.  Most likely you are within a wire or two in making the swap work.

 

Even with the best intentions, the authors of these on-line "How to Swap"  tutorials often leave out details or make mistakes that prove frustrating to people following the instructions given. Trust but verify.

 

There are many other Z car websites besides HybridZ  that detail this swap. Check those out too.

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The stock '76 electrical system is no longer in the car. It has the complete harness(efi harness, dash harness, etc.) from the '82-'83 zxt. The interior is stripped out. I will have to take photos of my wiring this weekend when I have a chance to work on the car in daylight so you guys can have a better idea of what I may be doing wrong

 

The bumble zee guide is for people swapping only the EFI harness,   Replacing the entire car's harness is a much bigger project.  Use the 1983 FSM Electrical chapters if you want to see the diagram of how Nissan did it.  A diagram is better than pictures.  

 

Seems like you've overshot your abilities and will have to get them caught up to what you're trying to do.  Worrying about "engine block getting 12 volts" shows that you're quite a way from where you should be.  Study up on basic automotive electrical concepts, like how and when current flows, what the voltage readings mean, what the fusible links are for, etc.  No offense intended.  You should be comfortable with this anyway after you get beyond this one simple problem.  There will be more, that are more complex.  

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Miles:

 

Thanks. I've looked at schematic of each user but up just have to study them a little lore. I've labeled most of the wires before cutting them but I should triple check them again.

 

That's true.but yes I have also read through other guides too.

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Since the entire harness from the zxt is being used, why doesn't the car run with everything plugged in as it would have been in a factory zxt?

 

inknow why there are fusible links. It can be replaced with maxi fuses. I may have a problem with the wiring but I'm not an idiot. But I appreciate the help

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I was just trying to make the point that fuses, fusible links, starters, alternators, etc. are pretty easy.  Complete wiring harness swaps are hard.  You have to break them down into components and sub-harnesses.  

 

Beside that your question is really "where is the short that's causing my fusible links to melt".  That's your #1 problem.  Not 12 volts to block, or why does'y my car run?

 

Just being blunt to let you know it's not going to be easy.  Good luck.  Take good measurements, measure continuity back to the positive and negative cables before connecting the battery to be sure things are right.

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Recommend that you buy this book: Basic Auto Electricity by StreetWorks Rod and Custom Products

 

 

 

 

http://www.watsons-streetworks.com/basic-auto-electricity-book

 

 

http://www.aplusrodandkustom.com/index.cfm/page/ptype=product/product_id=1913/category_id=117/mode=prod/prd1913.htm

 

 

 

You can buy it on-line or at your local speed shop.

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Edited by Miles

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Ok so I figured out why it was grounding. I had that black wire with the ring connector connected to the starter positive bolt. I removed it and I no longer ground the starter, but I have no idea where it goes. I also don't know where that yellow/red wire goes. Any help would be appreciated.

 

Now the new issue is that I don't think I'm getting any power to the ecu. The green LED doesn't light up when on the on position. I can hear the fuel pump relay clicking when turning the ignition switch to the on position. The starter also doesn't want to fully crank the engine. I can hear it engaging and trying to turn the flywheel but that's it. I will try to have the starter tested at the local parts shop tomorrow.

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