1973 240z Custom Wiring From Scratch

[Matthew Abate]

16 hours ago, Barefootdan said:

I may have missed it, but is there a reason to do this in the car rather than pulling everything out? Just curious 🙂 

I have pulled everything out. It's on a table in my office. That photo was from another thread.

[dutchzcarguy]

On 2/6/2023 at 7:31 PM, Matthew Abate said:

I have problems like these throughout all of my wiring across the entire car:

Often some PO just used bigger fuses and that's catastrophical for wiring.. never ever use bigger fuses and take care of contacts because dirty contacts make heat and distroy wiring harnesses also. 

[Matthew Abate]

1973 240z Heater Fan Blower Switch Harness (27155-E4400) Inventory
Position	Component	Connector Color	Connector Style	Direction	# of Pins	# of Wires	Sample Wire Color	Min. Feet of Wire Needed	Wire Gauge
1	Blower Switch	White	Nylon	Male	6	6	Black	[See Yellow Splice A]	12 AWG
							Red	[See Blue Splice A]	12 AWG
							Blue w/ White	[See Climate Control Face Harness]	14 AWG
							White	[See Blower Motor Resistors]	12 AWG
							Green	[See Blower Motor Resistors]	12 AWG
							Yellow	[See Blower Motor Resistors]	12 AWG
2	Blue Splice A	N/A	N/A	N/A	4		Red	1 (from Blower Switch)	12 AWG
							Red	[See Blower Motor Resistors]	14 AWG
							Red	[See Climate Control Face Harness]	14 AWG
							Red	[See Blower Power In]	12 AWG
3	Yellow Splice A	N/A	N/A	N/A	2		Black	1 (from Blower Switch)	12 AWG
							Black	[See Ground]	12 AWG
							Black	[See Blower Motor Resistors]	12 AWG
4	Ground	Black	Fork	N/A	1	1	Black	1 (from Yellow Splice A)	12 AWG
5	A/C Power	Clear	Bullet	Female	1	1	Blue	[See Blower Motor Resistors]	14 AWG
6	Blower Power In	Clear	Bullet	Male	1	1	Red	2 (from Blue Splice A)	12 AWG
7	Climate Control Face Harness	White	Nylon	Female	3	2	Red	2 (from Blue Splice A)	14 AWG
							–	–	–
							Blue w/ White	2 (from Blower Switch)	14 AWG
8	Blower Motor Resistors	White	Nylon	Female	6	6	White	2 (from Blower Switch)	12 AWG
							Red	2 (from Blue Splice A)	14 AWG
							Black	2 (from Yellow Splice A)	12 AWG
							Green	2 (from Blower Switch)	12 AWG
							Yellow	2 (from Blower Switch)	12 AWG
							Blue	1 (from A/C Power)	14 AWG

Edited February 11, 2023 by Matthew Abate

[Matthew Abate]

1973 240z Climate Control Face Harness (24026 N3300) Inventory
Position	Component	Connector Color	Connector Style	Direction	# of Pins	# of Wires	Sample Wire Color	Min. Feet of Wire Needed	Wire Gauge
1	Heater Fan Blower Switch Harness	White	Nylon	Male	3	2	Black	[See Ground]	14 AWG
							–	–	–
							Red w/ Blue	[See Red Splice A]	14 AWG
2	Red Splice A	N/A	N/A	N/A	4		Red w/ Blue	1 (from Heater Fan Blower Switch Harness)	14 AWG
							Red w/ Blue	[See Climate Control Light A]	14 AWG
							Red w/ Blue	[See Climate Control Light B]	14 AWG
							Red w/ Blue	[See Fan Switch Light]	14 AWG
3	Climate Control Light A	Black	Bulb	N/A	1	1	Red w/ Blue	1 (from Red Splice A)	14 AWG
4	Climate Control Light B	Black	Bulb	N/A	1	1	Red w/ Blue	1 (from Red Splice A)	14 AWG
5	Ground	Black	Fork	N/A	1	1	Black	1 (from Heater Fan Blower Switch Harness)	14 AWG
6	Fan Switch Light	Black	Bulb	N/A	1	1	Red w/ Blue	2 (from Red Splice A)	14 AWG

[Matthew Abate]

Okay, I need to move on to the next step and stop swirling on this diagram. Here it is in all of it's glory. I am pretty sure it is correct throughout but if anyone sees any errors, please let me know. It should be much more helpful for anyone with a 1973 than the ones previously posted since it is comprehensive and verified.

1973-240Z-Wiring-Diagram-Draft.pdf

 

So the next step is to make the changes that I intend to have in the car. Here's the list:

1. Convert to 280ZX distributor & E12-80 Ignition
    * Delete Ballast Resistor
    * Add ZX RF Resistor
    * Investigate and Update Condensers
    * Mimic 1979 280ZX wiring
    * Investigate 240z vs 280z tach issues more thoroughly
2. Change Alternator to Single Wire
    * Delete Voltage Regulator
    * Maintain Fuel Pump Wiring
3. Replace Heater Blower with AC
    * Delete Heater Blower Harness
    * Maintain Illumination for Controls
    * Add necessary AC Components
        * Add Wide Open Throttle Switch
        * Add Fan Temp Switch
        * Add Electric Fan Relay
        * Add Electric Fan
        * Add AC Thermostat Switch (mimic 1979 280ZX wiring)
        * Add AC Trinary Switch
        * Air Compressor
        * Add Air Conditioning Evaporator
        * Replace Throttle Opener with Fast Idle Control Device
            * Delete Throttle Opener Relay (refer to 1972 Wiring)
            * Remove Throttle Opener Solenoid
            * Investigate FICD Wiring
4. Replace Ammeter with Volt Meter
5. Change to Euro brake / signal configuration
    * Replace 240z turn signal switch with 260z turn signal switch
    * Update wiring at Combination Lights
    * Add 3rd Brake Light
6. Replace Cigar Lighter with 12-volt socket
7. Update Dashboard to LEDs
    * Investigate Dimmable LED bulbs
    * Investigate LED Dimmer to replace Rheostat
8. Consider Replacing Radio Wiring with Bluetooth Controls and Charging feeds
    * Investigate Bluetooth Controls
    * Investigate GPS Units
    * Investigate Backup Cameras
9. Add USB-C Wiring for charging
10. Determine if I need, and then find, new relays

Edited February 27, 2023 by Matthew Abate

[Matthew Abate]

I've been working on getting the correct wiring for my internally regulated 100-amp alternator into the diagram and have run into some interesting things while digging around. I think I have it pretty close, but I'm interested to see if anyone has any comments or alternative suggestions.

The reference material I have been looking at is mostly @bvolken's article on installing a 280ZX alternator, a general guide to installing 100-amp alternators in Z cars from the Edmonton Z Car Club, and random stuff about correctly wiring the GM alternator into other cars.

So, when looking at the wiring for the OEM alternator, this is what we start with:

I could just take all that out and go with a single wire setup, but I am opting for using the excite and sense wires for reasons outlined in the Edmonton article already mentioned. So based on what I have learned about this system so far, this is what I have:

 

A few things to note…

1. The combination of the voltage regulator and Fuel Pump Harness A (24032-N3300) created what amounted to a splice between the white wire coming off the engine harness and the yellow wire going to the fuel pump relay. I am preserving that here with a splice wrapped in light green tape. This will also supply a "Sense" wire for the alternator (terminal 2). I have read that it is better to have the "sense" wire come from something closer to the circuits for the accessories than directly from the battery, so I think repurposing / updating @bvolken's alternator wire rewire option gets me there. However, I am running my excite wire off the wire from the coil because it goes directly to the "on" position on the ignition, rather than using the BW/WB wires that originally went to the voltage regulator.

Here's an example of the direct wiring approach for reference:

2. I have retained the orange splice on the black wire with a white stripe that goes to the coil positive post from the "ON" position on the ignition switch, but now that wire is going to the "Lamp" or "Excite" wire for the alternator (terminal 1).

3. I have a 3-amp diode in the diagram, but I am uncertain about this addition. I will also be swapping my Ammeter out for a Voltmeter from a 260z, and those have the small red "Charge" light which sort of functions in a similar way by providing resistance until the alternator comes up to full speed. @SteveJ, I am curious about your opinion on this. Does having the diode AND the light create too much resistance, or can I get away with both?

Otherwise this isn't substantially different from the original circuits. You may have also noticed that I have deleted the seatbelt relay and the throttle opener relay. I think I have this done correctly but need to triple check it.

I might be adding a 120-amp circuit breaker on the red cable coming off the battery for extra extra extra protection, but I will definitely be replacing the fusible link on the starter with a resettable circuit breaker.

Edited February 27, 2023 by Matthew Abate

[SteveJ]

Here's my 2¢ on this. When I'm looking at fixing my engine harness, I'm thinking of using a relay controlled by the ignition power and having a constant voltage source that goes out to the L terminal of the alternator. This would eliminate the feedback on the ignition circuit that drives people to add the relay.

As for the diode and lamp being in the same circuit, resistance is a non-issue. Diodes don't have appreciable resistance. You will need keep the voltage lamp as an incandescent, though. That way if you start to see a glow in the lamp, you know the alternator is starting to fail.

[Matthew Abate]

13 hours ago, SteveJ said:

Here's my 2¢ on this. When I'm looking at fixing my engine harness, I'm thinking of using a relay controlled by the ignition power and having a constant voltage source that goes out to the L terminal of the alternator. This would eliminate the feedback on the ignition circuit that drives people to add the relay.

So the ignition controls the relay and that relay sends the constant voltage to the Alternator, or do you mean having a constant voltage source separate from the relay? What I am reading says not to have a constant voltage source to the L terminal that is not controlled by the switch. I think maybe you mean having the relay controlled by the switch, but I want to make sure we are saying the same thing.

 

13 hours ago, SteveJ said:

As for the diode and lamp being in the same circuit, resistance is a non-issue. Diodes don't have appreciable resistance. You will need keep the voltage lamp as an incandescent, though. That way if you start to see a glow in the lamp, you know the alternator is starting to fail.

Ah, right. Good point. The more I work on this the less convinced I am that I should change the dash lights to LEDs, but that one would be outside of the rheostat circuit so maybe it doesn't impact that choice.

[SteveJ]

Let me re-phrase. The 85 pin on the relay would come off a fuse fed by the black/white ignition wire. The 86 pin would be grounded. The 87 pin would be a constant voltage source, and the 30 pin would run up to the lamp light on the voltmeter. The other wire on the lamp light would run out to the L terminal (switched) on the alternator.

[Matthew Abate]

Fun story: I have been looking at the diagram of how to wire up a 280ZX distributor and couldn't for the life of me figure out why my BW wires didn't match the diagram. I chased the wires in my harnesses from the coil to the ignition and the tach and back again about six times, drew up how my wires are routed vs the FSM, and was about freak out before I realized that the wires for the ballast resistor and the coil have the same plugs and I just had them labeled wrong. I swapped the labels on my harness and now everything makes sense.

Derp.

 

6 hours ago, SteveJ said:

Let me re-phrase. The 85 pin on the relay would come off a fuse fed by the black/white ignition wire. The 86 pin would be grounded. The 87 pin would be a constant voltage source, and the 30 pin would run up to the lamp light on the voltmeter. The other wire on the lamp light would run out to the L terminal (switched) on the alternator.

Are you going to run the original alternator (or one from a 280zx)? Mine is the GM-style. Part of me wishes I had gone with a newer Nissan alternator instead, but I bought it back when I first bought the car and wasn't really thinking about this stuff then. I'm going to take a look at how your configuration would look in my situation, but relays are a subject I need to read up on before I can confidently mess with them.

Edited February 27, 2023 by Matthew Abate

[SteveJ]

1 hour ago, Matthew Abate said:

Fun story: I have been looking at the diagram of how to wire up a 280ZX distributor and couldn't for the life of me figure out why my BW wires didn't match the diagram. I chased the wires in my harnesses from the coil to the ignition and the tach and back again about six times, drew up how my wires are routed vs the FSM, and was about freak out before I realized that the wires for the ballast resistor and the coil have the same plugs and I just had them labeled wrong. I swapped the labels on my harness and now everything makes sense.

Derp.

I actually made a video on that subject to help people who get confused when they disconnect the wires from their ballast resistor and coil.

1 hour ago, Matthew Abate said:

Are you going to run the original alternator (or one from a 280zx)? Mine is the GM-style. Part of me wishes I had gone with a newer Nissan alternator instead, but I bought it back when I first bought the car and wasn't really thinking about this stuff then. I'm going to take a look at how your configuration would look in my situation, but relays are a subject I need to read up on before I can confidently mess with them.

I have been using the ZX alternator for over 20 years, and the GM "one wire" operates pretty much the same way. 

As far as relays go, you may want to read this: https://fiddlingwithzcars.wordpress.com/2012/12/22/relays-simplified/

[Matthew Abate]

On 2/27/2023 at 6:41 PM, SteveJ said:

As far as relays go, you may want to read this: https://fiddlingwithzcars.wordpress.com/2012/12/22/relays-simplified/

Thanks. I will read up on them.

As I am working in integrating my ZX distributor into my wiring, I noticed quite a few threads here and over at Hybridz where people say you can live without the condenser that is NLA for those cars. This was the 2-wire condenser that plugged into a wire coming out of the distributor on one end and spliced into the BW wire going to the electronic ignition on the other. I'm also noticing that in the ZX the condenser joins up to wires going to the fuel pump and the ignition switch, whereas the 240z has the condenser on a wire that goes to the seat switches, fuse box, hazard switch and some gauges. Curious if anyone has any thoughts on this.

Right now I am leaning toward keeping the 240z setup for that specific component.