wiring help

[Empire motorsports]

So this is my first datsun project i have a 1977 280z i put the engine, transmission from a 1978 280z along with the 1978 harness for the engine i was wondering what needs to be converted in order for the engine harness to work with the dash harness? if anyone can help point me in the right direction i would appreciate it im new to the forum or to any forum to be quite honest so im not to adequate in navigating.  

[Zed Head]

The 77 parts will run the 78 engine just fine.  If you can go back, that might be the way to do it.  78 used a different fuel pump control system, and EFI power relay.  That's the main difference you need to deal with.  It's not really connected to the dash harness although some wires might be in similar locations.  You can work around the fuel pump power control if you need to use the 78 AFM.

Download the two FSM's and compare the wiring diagrams in the Engine Fuel chapters.

http://www.classiczcars.com/files/category/13-280z/

[Zed Head]

The 77 parts will run the 78 engine just fine.  If you can go back, that might be the way to do it.  78 used a different fuel pump control system, and EFI power relay.  That's the main difference you need to deal with.  It's not really connected to the dash harness although some wires might be in similar locations.  You can work around the fuel pump power control if you need to use the 78 AFM.

Download the two FSM's and compare the wiring diagrams in the Engine Fuel chapters.

http://www.classiczcars.com/files/category/13-280z/

[Empire motorsports]

ive heard that that the late 77 and 78 models wiring was similar my 77 is the is the early model im just worried the engine controls wont be able to work. but ill take a look at it and see what i can do thanks for the reply

 

[SteveJ]

Blue's Tech Tips probably has better drawings of the wiring diagrams than you'll find the in FSM.

Be aware that if you are using the 78 engine harness, you will need an internally regulated alternator. The 78 wiring harness doesn't accommodate an external voltage regulator. 

[Zed Head]

Hey, just to be clear, the EFI harness is almost completely separate from all of the other harnesses.  That's why the Engine Fuel chapter, with it's diagram of the sub-harness is a good place to start.  You can swap in the EFI harness without messing with alternator harness, for example.  The bigger diagrams will show wire colors for doing actual work but the basics are in the small diagram.  Some of the bigger diagrams are also on the CZCC forum.

Also, I just remembered that my 1978 parts car had the AFM fuel pump relay switch even though the EFI harness didn't use it.  It was there but not used.  It worked fine I used the AFM for quite a while in my 1976 car.  

Much simpler to use the 1977 wiring and just change a few small things, than to try to swap the 78 wires in, I'd think.  Good luck and don't assume that ugly wire splices are from a PO.  Nissan used some nasty looking crimped connections.

http://www.classiczcars.com/files/category/1-wiring-diagrams/

Edited December 14, 2016 by Zed Head