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I am putting the engine back together on my 1978 280z. Ran into a couple of wiring questions.  More specifically, I have no idea what they connect to! 

 

I have two wires with bullet connectors coming out of the harness near the positive and negative ignition coil wires. One is blue and the other is white.  

image.png.b94646f751dfb19198bb1a9b6b89f39b.png

 

This wire is broken but I do not see what it used to connect to.  This mounts to the screw for the ignition coil
image.png.457f9d0ef770b36d7983583f8bb93afa.png

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7 hours ago, Gotham22 said:

I am putting the engine back together on my 1978 280z. Ran into a couple of wiring questions.  More specifically, I have no idea what they connect to! 

 

I have two wires with bullet connectors coming out of the harness near the positive and negative ignition coil wires. One is blue and the other is white.  

image.png.b94646f751dfb19198bb1a9b6b89f39b.png

 

This wire is broken but I do not see what it used to connect to.  This mounts to the screw for the ignition coil
image.png.457f9d0ef770b36d7983583f8bb93afa.png


I would use a test light and use the ignition diagram in the Haynes manual. There are not many leads that connect to the coil and/or distributor. If your wiring is OEM, the wiring diagram may have the color of the conductors. I know my Z31 Haynes manual did. 

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From my recent experience with sorting out and selling the L28 from my 240Z, and helping a friend with a SpeedHut gauge install, it seems that even when the Z’s were new (Before previous owners started hacking up the harnesses for whatever reasons) is that there were a handful of stock wires that seemed to serve no purpose and don’t really go anywhere. My guess is that nearly all the harnesses from 70’s Z cars were designed with automatic transmission wiring and factory option wiring installed to save time and money. Unfortunately the Haynes manual doesn’t show these wires in specific diagrams so if you had factory AC originally or if this is a manual trans, you may want to look for for some community made diagrams instead of the Haynes.

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@Gotham22

Yeah the AC wiring complicated the wiring around the front cover a fair on the early Z’s. My 73 240Z had dealer installed AC that had already been removed when I purchased the car. I found about 5 wires associated with it bundled into the harness that were cut and terminated, but visible which made tracing some stuff difficult. And these wires weren’t referenced in the Haynes manual. The 280Z diagram may actually have AC wiring because it was probably a bit more common addition around the end of the 70’s. 
AC wiring is a good place to start, but have you done any (or previous owner done any) mods to the ignition system? If you have the 280ZX dizzy and module, or HEI module than there are some things that get bypassed and deleted in that area of the harness. On the 240Z it’s the ballast resistor, on the 280Z I believe they would bypass the Ignition Transistor module. That would be another good place to start looking.

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