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HELP On My Own 1973 Body Harness Near Completion

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Hello z members,


I am in need of help and need your expertise on my body wiring harness. On paper I have a 1972 240z. However, it seems like the body harness is from a 1973 because of the 4 different color connectors at the beginning of the harness (Black, Blue, Green, and White).




After looking around online for a couple weeks and looking at the 1970 – 74 body harness on www.xenons30.com trying to find out what year my harness is from and what connector goes where, I have decided to create my own wiring diagram. Reason why is first, the wire colors don’t exactly match to any of the Factory service manual body wiring diagram for any of the z years. Second, the previous owner cut and added a lot of wires to the harness. Third, I have a L28ET engine that I will be dropping (not sure if this will matter much).




I have completed about 85 to 90 % of the wiring diagram for a “1973†body harness. I can’t complete the rest because I have 9 unknown wires that I don’t know where they go. There are 3 wires from the blue Connector A (yellow/green, red/black, and red), 2 wires from the black Connector C (black and red/blue), 3 wires from the white Connector D (green/white, black, and yellow/white), and 1 wire from the Throttle Pener Relay (black/yellow).




Can someone please help me find where these wires go and or connect to please?


I have a pic of what I have completed so far for the diagram.



Many thanks


Edited by mainboyd
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I can confirm you have a 73 harness because of those 4 colorful big block connectors that mate to the 73 dash harness. The 74 harness also had this, but also had much more. The one engine glaring difference is the fusable link box and the shunt box for the ammeter. If you don't have those, then you definitely have a 73 harness.


I agree that the schematics from the FSM's for these years aren't a whole lot of help, but the body electrical section has some wiring plug ID and location diagrams that might be helpful.


Few here including me can tell you off the top of our what wire goes where between the two years without some research.


The only really big wiring difference up front that pops into my head is the intermittent wiper motor and its underdash relay/controller that was added in 73.  The carbs had some electrical controls as well didn't they? Maybe you have an auto harness that had an interlock relay?


Perhaps approach this from the functionality point of view. Get the major systems like lights, ignition, voltage reg, oil pressure, starter, wipers, etc working and diagramed then worry about the left over wires....

Edited by z240
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OK so I laid down my body harness on the floor, roughly placing/laying the wires and connectors where they would be located if in the car and took a picture just so we all know what unknown wires im talking about.

And sorry about the poor quality 3G iphone pic...


There are also some connectors that just have " ? " because I don't know the description of them (Red/White wire & White wire)



Edited by mainboyd
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The big White & White/Red are main power connections (+12V).  Refer to the circuit diagram as to how they connect.  The additional wiring that goes past your left-side lighting & horn end up at the coil / ballast / distributor / water temp sender (don't remember what all) - All that should be in the circuit diagram as well.  The long wires on the top of your picture probably cross the firewall to the windshield washer motor? and the brake switch?

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ok so I was able to figure out what wires go where for the coil and the ballast.


Here is an update of my 1973 240z body wiring harness (please feel free to let me know if I wired anything wrong):



I just have a few more wires that I don't know where they go.

Few of the questions relate to these wires that I have circled with green;



-In the pictures below I have 2 red with black stripe wires (one of the wires turns into a blue with red stripe wire) that seem like they would go to the same component however, I don't know what that would be. When pulling the harness out, a part fell. What is that? Is that where the 2 wires go?



-In these next pictures below I have two wires, one Black wire and the other is black with yellow stripe(connects to the same blue with red stripe wire from my first question) that are connected to each other at the end. It follows the yellow with green stripe wire that is I believe for the "brake switch". It seems like the previous owner did some custom work with this section of the harness and just had these two wires connected at the end.


- Last is the 2 wires at the very end of the harness, yellow with white stripe wire and black with yellow stripe wire. Where do these go? You can see them on the diagram I put together.


Many thanks,




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The little round switch in post 7 is the back up light trigger switch that goes in your transmission.


The brake light switch is similar, but generally cleaner, has smaller threads, and likely has a lock nut on the threads to lock the position once its aligned to the brake pedal action.


The last three wires in the last pair of pictures in post 7 are to the washer bottle (pair) and the long one with a round bullet connector goes to the brake balance/warning switch on the brake line below brake master on the side wall down there by the frame rail.


That should just about do it.

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z240 THANK YOU!!!!

That helped me a lot and clarified a few things for me.


I have one more question about the harness and I believe I will be finally done with it once I figure out where they go.

Would anyone know where the last 2 wires at the very end of the harness go? One is a long yellow with white stripe wire and the other is a shorter black with yellow stripe wire. The picture bellow shows what 2 wires im talking about with the green arrows pointing at them.




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ok thanks!


I will look more into that black and yellow wire.

It seems like another z owner from the classic zcar club website had the same question about that black with yellow stripe wire, here is the link to the page: http://www.classiczcars.com/forums/electrical-s30/47698-trying-get-my-tach-back-73-240z.html


You think its for the "throttle opener"?

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