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77 280z ls1 swap electrical wiring questions

11633 Views 18 Replies 4 Participants Last post by  perzn
hi guys, I have a 77 280z that i am dropping in an ls1. I am using a standalone harness. my questions is what datsun wiring is needed and not needed to still use accessories such as radio, headlights, dash lights and etc. because i have seen photos of almost no wiring in the engine bay and i am trying to clean up the engine bay to repaint and i dont want to risk removing wires that i might still need. all help is appreciated, thanks
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What I did was remove the stock harness then painted the bay. The LS1 harness is only for the engine not the body harness that runs over by the fuse block.

The standalone harness should just have connections for;

Switched 12v (ignition)
fuel relay
starter solinoid
and ground.

At least thats how it was with my lt1 harness.

You can ask/search over on hybridz.org in the gen IV/V subforum.
thanks for the reply. yea i signed up on hybridz to post since i couldnt find an answer, it wont let me post since i am still a newbie on that site and recently i was blocked from logging in for some reason.

correct, the harness has a fuse block with like 8 fuses. i am just trying to get rid of wires that i am not using so my engine bay doesnt look rigged and messy. any wires being re-used from any of those 2 harnesses(on the passenger corner and driver side corner). this is my first time doing a swap everything is going smoothly, just fuel routing and wiring giving me slight problems, but mostly wiring.
I just pulled my dash to clean up the wiring and to re-route it to the engine bay. I'll also be attempting to repair the cracks in the dash pad at the same time.
Same here. Ijustpicked up some great stuff and plastic repair epoxy today, going to repair it myself with the dash restore write up on classiczcar.com.

What wires did you clean up? Should I just cut or clean up all the wiring from the fusible link box(passenger side) and wires that came off the msd ignition(drivers side)?

Or just tell me which wires willnot be reusable in the engine bay. Or am I going to remove all wiring from dash and rewire all of it...
That depends on if you are going to use aftermarket gauges or the stock ones. Your also going to want to keep the wires for the lights and signal system. Also do you plan on keeping the a/c and heater system?

Mine car is gutted as far as a/c and heat, so I was able to get rid of that wiring. (I just re-wrapped the stock harness and tucked it away. No point in actually cutting all that wire in case i need it later for something).
I'm going to reuse stock gauges with jci's speedometer calibration kit. No I'm not going to be using ac at the moment, I disconnected all the ac lines and removvved them and ac condesnser.

I guess I'm going to tape all the other wires to the body harness than. Should I just leavve ithe harness t at the frame rail ? What about the standalone harness? I'm deciding to but the ecu under the dash, should I cut up the gromet on passenger side to guide the wiring through the firewall?
I am new to the site, and I am here to get questions answered in regard to buying a Z of my own so I dont have many answers to your current problem. However I am a mechanic with my a/c licence and if you plan on reusing your removed a/c components make sure that all openings are sealed as air tight as you can, compresser, lines, condensor, evaperator. Dont worry about the reviever/dryer just get a new one. Also I would sujest you turn the compresser over once in a while (just a turn by hand is fine). With all that said if it was r-12 you will probably need to replace some parts to retrofit to R-134 as R-12 is outdated. I hope that I may have helped prevent a future issue and not wasted your time.
thanks for the tip but im not going to be using a/c at the moment, so my belt is just using alternator, water pump, crank shaft pulley, tensioner pulley and idler pulley. no a/c cpmpressor attached but i will use a/c somewhere down the road when my money piles back up:)
You'll still need the harness that is on the passenger side of the car. That harness is your lights, horn, alt, ect.

The harness you won't need is the stock ecu one thats on the drivers side kick panel.
You should really get a wiring diagram, figure out which wires you will need to mess with/splice and label them... Next figure out what wires you wont need and remove them (if possible). Then whatever you have left run it nice n tight against th frame rail like it was from the factory. (might have to move it a lil to keep it away from the passenger side header)
Hmm well the harness on the driverside their are afew wires that go straight to the body harness and also their is a wire that wentstraight to the coolant sensor onthe l28 setup.

On the passenger side harness the transistors look like they arepart of apower source.

Can someone check out the diagram and list the wires that can be deleted or rerouted. My resource for the diagram is on 4moores.com/files , scroll down and their is a thumbnail for the 77 z diagram. Please someone just help me with mostly the wiring and maybe fuel system, the rest is just cake. Thanks.
The harness on the drivers side goes to the stock computer and the EFI. Just take out that harness and ditch the ecu (sell them in the for sale section).

I disconnected the EFI relay on the passengers side and now I have all my lights working minus the right turn signal (need to get a new bulb).
Sweet! Thattakes careof the driver side. But the passeneger side icouldtape up some plugs but what about the fusiblelings theyrea little too bigto justtape up. Cani just wire a straight wire through or substitute the fusible links into fuses?
You can upgrade those fuseable's to maxi-fuse. I will do that soon myself.
alright, i cut the transmission ears off. installed new brake booster and master cylinder. engine bay is painted. just installed the clutch, flywheel and transmission.

for location of the ecu, where is the best location to install it? driver side cabin or passenger side cabin? my standalone harness came with a 2inch diameter grommet. i also thought about routing the standalone through the datsun ecu hole on drivers side. need some input.

also on my standalone harness has 7 wires, i guess i have to splice into(?) not sure. need input on best ecu location to install these wires.
wires are:

(brown)- ignition feed(from relay center)
(green)-fan 1(optional)
(brown)-MIL ground
(purple)-brake signal/tcc ground
(orange)-park neutral
(blue)-fan 2(optional)
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