1973 240z Custom Wiring From Scratch

[Matthew Abate]

Table Number 3!

This table represents half of the dashboard harness for a 1973 240z (PN 24013-M3321). It's… okay. There are three items and a missing wire I can't identify (pink cells) and I am unsure about what I marked as the heater (bright yellow cells), but it's close. The other half will be in the next table.

Note: I'll post the wire lengths later.

1973 240z Dashboard Harness (24013-M3321) Inventory
Position	Component	Connector Color	Connector Style	Connector Image	Direction	# of Pins	# of Wires	Diagram Wire Color	Sample Wire Color	Min. Feet of Wire Needed
1	Body Harness	Blue	Nylon 10-Prong		Male	10	10	White w/ Black	White w/ Black	[See Speakers & Radio]
								Blue w/ Red	Blue w/ Red	[See Power Antenna Switch]
								White	White	[See Speakers & Radio]
								Blue w/ White	Blue w/ White	[See Power Antenna Switch]
								Yellow	Yellow	[See Ammeter & Fuel Gauge]
								Green	Green	[See Electric Fuel Pump]
								Green	Green	[See Engine Harness D]
								Green	Green	[See Engine Harness B]
								Green w/ Red	Green w/ Red	4 (to Yellow Splice)
								Green w/ Black	Green w/ Black	4 (to Gray Splice F)
2	Engine Harness B	Green	Nylon 10-Prong		Male	10	7	Green	Green	1
								Green	Green	4 (to Lt. Blue Splice D)
								Black w/ Yellow	Black w/ Yellow	[See Ignition Switch]
								Green w/ Red	Green w/ Red	5 (to Lt. Blue Splice G)
								Green w/ Black	Green w/ Black	4 (to Gray Splice E)
								Black	–
								Black	Black (Heavy)	1 (to Green Splice A)
								Yellow w/ Red	Yellow w/ Red	[See Switch Element]
								–	–	–
								–	–	–
3	Engine Harness D	Black White	Nylon 10-Prong		Male	10	8	Blue w/ Red	Blue w/ Red	2 (to Lt. Blue Splice B)
								Yellow w/ Black	Yellow w/ Black	[See Water Temperature & Oil Temperature Gauge]
								Black w/ White	Black w/ White	4 (to Green Splice D)
								Green	Green	1
								Yellow w/ White	Yellow w/ White	[See Water Temperature & Oil Temperature Gauge]
								Green w/ White	Green w/ White	4 (to Green Splice F)
								Black w/ White	Black w/ White	[See Tachometer]
								Green w/ White	Green w/ White	[See Hazard Switch]
								Blue w/ White	Blue w/ White	4 (to Gray Splice C)
								–	–	–
4	Engine Harness E	White	Nylon		Male	1	1	White w/ Red	White w/ Red (Heavy)	1 (to Gray Splice A)
5	Accessory Relay	White	Nylon			4	3	Blue	Blue	4 (to Red Splice)
								Blue	Blue	[See 30-Amp Fuse]
								–	–	–
								Blue	Blue	[See Heater]
6	Rear Window Electric Defroster Relay	White	Nylon			4	4	White w/ Red	White w/ Red (Thick)	[See 20-Amp Fuse]
								Blue w/ Red	Blue w/ Red	[See Rear Window Electric Defroster Switch]
								Black	Black	1 (to Green Splice A)
								Red w/ Blue	Red w/ Black (Thick)	[See Junction 1A]
7	?	Clear	Bullet		Female	1	1		Blue w/ Red	2 (to Lt. Blue Splice B)
8	Junction 1A	Clear	Bullet		Male	1	1	Red w/ Black (Thick)		1
	Light Blue Splice A	N/A	N/A	N/A	N/A	2		Green		N/A
								Green
	Green Splice A	N/A	N/A	N/A	N/A	2		Black		N/A
								Black(Heavy)		2 (to Green Splice B)
	Light Blue Splice B	N/A	N/A	N/A	N/A	2		Blue w/ Red		N/A
								Blue w/ Red
	Green Splice B	N/A	N/A	N/A	N/A	4		Black (Heavy)		4 (to Green Splice D)
								Black		N/A
								Black
								Black
	Light Blue Splice C	N/A	N/A	N/A	N/A	4		Green		N/A
								Green
								Yellow
								Yellow w/ Red
	Gray Splice A	N/A	N/A	N/A	N/A	2		White w/ Red (Heavy)		N/A
								White w/ Red
9	Junction 1B	Clear	Bullet		Female	1	1	Black		3
	Light Blue Splice D	N/A	N/A	N/A	N/A	2		Green		N/A
								Green
10	Speakers & Radio	White	Nylon		Male	3	3	White w/ Black	White w/ Black	4
								White	White	4
								Blue	Blue	1 (from Red Splice)
11	Power Antenna Switch	White	Nylon		Female	3	3	Blue w/ White	Blue w/ White	4
								Blue	Blue	1 (from Red Splice)
								Blue w/ Red	Blue w/ Red	4
12	Heater	Clear	Bullet		Female	1	1	Red	Blue	4
13	Buzzer	White	Nylon		Female	3	3	Black	Black	[See Door Switch LH]
									Black	3 (to Green Splice C)
								Green	Green	2 (from Lt. Blue Splice D)
	Green Splice C	N/A	N/A	N/A	N/A	2		Black		N/A
								Black
14	30-Amp Fuse	White	Fuse		N/A	2	2	Blue	Blue	4
								Red	Blue	X (to Gray Splice B)
15	20-Amp Fuse	White	Fuse		N/A	2	2	White w/ Red	White w/ Red	5
								White w/ Red	White w/ Red	3 (to Gray Splice B)
16	Choke Warning Light	White	Nylon		Male	3	2	Black	Black	2 (from Green Splice C)
								–	–	–
								Red w/ Blue	Red w/ Blue	[See Seatbelt Warning Light]
17	Rear Window Electric Defroster Switch	White	Nylon		Female	3	3	Blue	Blue	1 (from Red Splice)
								Blue w/ Red	Blue w/ Red	5
								Black	Black	3 (from Green Splice C)
18	Electric Fuel Pump	White	Nylon T			2	2	Black	Black w/ White	2 (to Green Splice D)
								Green	Green	5
19	Seatbelt Warning Light	White	Nylon			4	4	Red	Red	2 (to Lt. Blue Splice E)
								Green	Green	3 (from Lt. Blue Splice D)
								Black	Black	3 (from Green Splice C)
								–	Red w/ Blue	5
	Red Splice	N/A	N/A	N/A	N/A	4		Blue		N/A
								Blue
								Blue
								Blue
	Gray Splice B	N/A	N/A	N/A	N/A	3		White w/ Red (Heavy)		N/A
								White w/ Red (Thi)ck
								Blue
	Light Blue Splice E	N/A	N/A	N/A	N/A	2		Red		N/A
								Green
20	Fuse Box A	White	Nylon			6	6	Green w/ Yellow	Green w/ Yellow	3 (to Gray Splice C)
								Green w/ White	Black w/ White (Thick)	4 (to Green Splice D)
								Blue w/ Red	Blue w/ Red	[See Ignition Switch]
								Blue	Blue	1 (to Red Splice)
								Blue w/ Red	Blue w/ Red	3 (from Lt. Blue Splice B)
								Green	Green	2 (from Lt. Blue Splice E)
21	Fuse Box B	Black	Ring w/ Cap (Nylon in FSM)		N/A	1	1	White w/ Red (Heavy)	White w/ Red (Heavy)	3 (from Gray Splice B)
22	Fuse Box C	Clear	Bullet		Male	1	1	Blue w/ White	Blue w/ White	[See Cigar Lighter]
	Green Splice D	N/A	N/A	N/A	N/A	3		Black w/ White		N/A
								Black w/ White
								Black w/ White (Heavy)		3 (to Green Splice G)
	Gray Splice C	N/A	N/A	N/A	N/A	2		Blue w/ White		N/A
								Green w/ Yellow
23	Clock	Clear	Bullet		Male	1	1	Black	Black	1 (to Green Splice E)
24	Map Light	Clear	Bullet		Male	1	1	Black	Black	3 (from Green Splice B)
25	Ammeter & Fuel Gauge	White	Nylon		Female	4	3	Black	Black	1 (to Green Splice E)
								–	–	–
								Yellow	Yellow	4
								Yellow w/ Red	Yellow w/ Red	3 (from Lt. Blue Splice C)
26	Ammeter	Black	Ring w/ Cap (Nylon in FSM)		N/A	1	1	White w/ Red (Heavy)	White w/ Red (Heavy)	2 (from Gray Splice D)
	Gray Splice D	N/A	N/A	N/A	N/A	3		White w/ Red (Heavy)		3 (from Gray Splice A)
								White w/ Red (Heavy)		N/A
								White w/ Red (Heavy)
	Gray Splice E	N/A	N/A	N/A	N/A	3		Green w/ Black		N/A
								Green w/ Black
								Green w/ Black
	Green Splice E	N/A	N/A	N/A	N/A	2		Black (Heavy)		N/A
								Black
	Light Blue Splice F	N/A	N/A	N/A	N/A	3		Green w/ Red		N/A
								Green w/ Red
								Green w/ Red
27	Water Temperature & Oil Temperature Gauge	White	Nylon		Female	4	4	Yellow w/ Black	Yellow w/ Black	4
								Black	Black	4 (from Green Splice E)
								Yellow w/ White	Yellow w/ White	4
								Yellow	Yellow	X (from Lt. Blue Splice C)
	Light Blue Splice G	N/A	N/A	N/A	N/A	3		Green		N/A
								Green
								Green w/ Yellow
28	Cigar Lighter	Black	Spade		Male	1	1	Black	Black	2 (to Green Splice G)
		Clear	Bullet		Female	1	1	Blue w/ White	Blue w/ White	4
29	Hazard Switch A	White	Nylon		Female	3	3	Green w/ Yellow	Green w/ Yellow	[See Brake Light Switch]
								White w/ Black	White w/ Black	2 (from Gray Splice F)
								White w/ Red	White w/ Red	1 (to Yellow Splice)
30	Hazard Switch B	White	Nylon		Female	6	6	Green	Green	1 (from Lt. Blue Splice G)
								Green	Green	[See Turn Signal Flasher Switch]
								Green w/ Yellow	Green w/ Yellow	3 (from Gray Splice C)
								Green w/ Black	Green w/ Black	2 (from Gray Splice E)
								Green w/ Red	Green w/ Red	3 (from Lt. Blue Splice F)
								Green w/ White	Green w/ White	4
31	Hazard Switch C	Clear	Bullet		Female	1	1	Black	Black	2 (to Green Splice G)
	Gray Splice F	N/A	N/A	N/A	N/A	2		Green w/ Black		N/A
								White w/ Black
	Yellow Splice	N/A	N/A	N/A	N/A	2		Green w/ Red		N/A
								White w/ Red
32	Tachometer	White	Nylon		Female	4	4	Black	Black	2 (to Green Splice G)
								Black w/ White	Black w/ White	5
								Green w/ White	Green w/ White	2 (to Green Splice F)
								Green	Green (Spliced to Red w/ Blue)	3 (from Lt. Blue Splice G)
33	Turn Signal Indicator Light LH	Black	Blulb		N/A	1	1	Green w/ Red	Green w/ Red	2 (from Lt. Blue Splice F)
34	Turn Signal Indicator Light RH	Black	Blulb		N/A	1	1	Green w/ Black	Green w/ Black	2 (from Gray Splice E)
35	Switch Element	White	Nylon		Female	3	2	Yellow	Yellow	2 (to Green Splice H)
								–	–	–
								Yellow w/ Red	Yellow w/ Red	5
	Green Splice F	N/A	N/A	N/A	N/A	2		Green w/ White		N/A
								Green w/ White
	Green Splice G	N/A	N/A	N/A	N/A	4		Black (Heavy)		N/A
								Black
								Black
								Black
	Green Splice H	N/A	N/A	N/A	N/A	2		Black w/ White (Thick)		N/A
								Yellow
36	Brake Indicator Light	Black	Bulb		N/A	2	2	–	Green w/ Yellow	2 (from Lt. Blue Splice G)
								Yellow w/ Blue	Yellow w/ Green	[See Hand Brake Junction]
37	Hand Brake Junction	Clear	Bullet		Female	1	1	Yellow w/ Green		1
38	Door Switch LH	Clear	Bullet		Female	1	1	Black	Black	6
39	Turn Signal Flasher Switch	White	Nylon		Female	2	2	Green	Green	6
								White	White	[See Combination Switch B]
40	Brake Light Switch	Clear	Bullet		Female	1	1	Green w/ Yellow	Green w/ Yellow	6
		Clear	Bullet		Female	1	1	Green w/ Yellow	Green w/ Yellow	[See Turn Signal Switch]
41	Turn Signal Switch	White	Nylon		Female	6	5	Green w/ Yellow	Green w/ Yellow	6
								Green w/ Red	Green w/ Red	2 (from Lt. Blue Splice G)
								Green w/ Black	Green w/ Black	3 (from Gray Splice E)
								–	–	–
								Green w/ Black	Green w/ Black	3 (from Gray Splice F)
								Green w/ Red	Green w/ Red	3 (from Yellow Splice)
	Gray Splice G	N/A	N/A	N/A	N/A	3		White w/ Red (Heavy)		3 (from Gray Splice D)
								White w/ Red (Heavy)		N/A
								White w/ Red (Heavy)
42	Ignition Switch	White	Nylon		Female	6	5	–	–	–
								Blue w/ Red	Blue w/ Red	6
								White w/ Red	White w/ Red (Double Thick)	2 (from Gray Splice G)
								Black w/ Yellow	Black w/ Yellow (Thick)	6
								Black w/ White	Black w/ White (Thick)	3 (from Green Splice H)
								Green w/ White	Green w/ White	3 (from Green Splice F)
43	Junction 1C	Clear	Bullet		Female	1	1	Blue w/ Red		6 (from Lt. Blue Splice B)
44	Combination Switch A	Black	Spade (Large)		Male	1	1	Black	Black (Heavy)	2 (from Green Splice G)
45	Combination Switch B	Black	Spade		Male	1	1	White	White	6
46	Combination Switch C	Clear	Bullet		Female	1	1	White w/ Red	White w/ Red (Thick)	2 (from Gray Splice G)

Edited August 24, 2022 by Matthew Abate

[SteveJ]

This may help you with identification

[Matthew Abate]

15 hours ago, SteveJ said:

This may help you with identification

Oh man, this is so helpful! Thank you. I keep forgetting about the speakers.

I'll make these updates in my previous post.

The position of the blue with red stripe wire at position #7 is right out the big colored connectors. It is spliced to a blue / red wire that goes to the fuse box and another one of the same color for the junction connector that comes out at the ignition switch.

It has something to do with the wipers. The wiring diagram shows 3 blue w/ red wires: one going from the ignition switch to the fuse box, one out of the fuse box to the wiper motor, and one from the combination switch and connecting to a yellow / white wire that goes to the wiper fluid bottle.

Edited August 24, 2022 by Matthew Abate

[SteveJ]

So for #7, the LR wire coming off the fuse box goes in several directions.

1. It turns into BY and goes out to the washer
2. It goes to the Intermittent Relay for the wipers as LR
3. It turns into R and goes out to the reverse switch (and inhibitor switch on the automatic).

There is another LR wire that goes from the defroster switch to the defroster relay.

I think there is a mistake on the wiring diagram for the intermittent relay. It shows the LR wire from the fuse box turning into BY when it gets to the intermittent relay, and another LR wire on the intermittent relay that goes to the wiper motor as BY. My guess is that BY and LR are swapped on the intermittent relay.

Can you post a photo of #7 with a little more context in the wire bundle? That may help narrow it down.

[Matthew Abate]

2 hours ago, SteveJ said:

Can you post a photo of #7 with a little more context in the wire bundle? That may help narrow it down.

Here you go. It's the one in the black sheath with a female bullet connector pointing to the top of the photo (between the blue wires and the white wire w/ the red stripe).

Edited August 24, 2022 by Matthew Abate

[SteveJ]

9 minutes ago, Matthew Abate said:

Here you go. It's the one in the black sheath with a female bullet connector pointing to the top of the photo (between the blue wires and the white wire w/ the red stripe).

 

Perfect. Now I can look for it in my car.

[SteveJ]

Found it

 

Here are wires going to the intermittent relay:

Obviously, the wiring diagram in the FSM isn't quite right for the intermittent relay as it shows 9 wires. There isn't a BY wire going to the relay, and there is only one ground wire.

 

[Matthew Abate]

Amazing!

So not only does that solve #7 in harness #1, it solves for position #5 in harness #2, which you would not know because I have not posted the table for yet. The only mysteries I will have left are the 4 wires that are missing (2 from the dash and 2 from the engine) and a blue connector on this harness I am chasing now, which might be to the radio lights. Maybe I can find those using the diagrams.

Edited August 25, 2022 by Matthew Abate

[Matthew Abate]

Table Number 4!

This table represents the other half of the dashboard harness for a 1973 240z (PN 24013-M3322). It was much easier than the other half. There only two items I couldn't figure out: a missing wire in the blue 10-pin connector to the engine harnes and a blue wire near the fuse box branch what might be power to the Radio (pink cells).

Pretty close to done with this inventory now. I have some small harnesses to capture still (fuel pump harnesses and the heater controls harness), but I don't think I need them for my final build so I may do that later.

1973 240z Dashboard Harness (24013-M3322) Inventory
Position	Component	Connector Color	Connector Style	Connector Image	Direction	# of Pins	# of Wires	Diagram Wire Color	Sample Wire Color	Min. Feet of Wire Needed
1	Engine Harness A	Blue	Nylon 10-Prong		Male	10	9	Blue w/ White	Blue w/ White	1 (to Lt. Blue Splice D)
								Red	Red	[See Fog Light Switch]
								Black w/ Yellow	–
								Red w/ Black	Red w/ Black	[See Body Harness Aux]
								Yellow w/ Green	Yellow w/ Green	1 (to Lt. Blue Splice A)
								Red w/ Black	Red w/ Black	[See Light & Horn Switch]
								Red w/ White	Red w/ White (Thick)	5 (to Gray Splice)
								Green w/ Black	Green w/ Black	[See Light & Horn Switch]
								Green w/ Red	Green w/ Red	[See Fuse Box D]
								–	–	–
2	Engine Harness C	White Black	Nylon 10-Prong		Male	10	8	Red w/ Blue	Red w/ Blue	[See Combinations Switch E]
								Red	Red (Thick)	3 (to Brown Splice)
								Green w/ Blue	Green w/ Blue	1 (to White Splice A)
								Red w/ Blue	Red w/ Blue	[See Fuse Box D]
								Red w/ Yellow	Red w/ Yellow (Thick)	[See Fuse Box D]
								Blue w/ Yellow	Blue w/ Yellow	[See Combinations Switch E]
								Yellow w/ Black	Yellow w/ Black	[See Combinations Switch E]
								Black	Black	2 (to Lt. Blue Splice C)
								–	–	–
								–	–	–
3	Engine Harness F	White	Nylon		Female	1	1	White	White (Heavy)	2 (to Yellow Splice A)
4	Intermittent Relay	White	Nylon		Female	6	4	Blue w/ White	Blue w/ White	2 (to Lt. Blue Splice C)
								Blue	Blue	[See Combinations Switch E]
								Blue w/ Red	Blue w/ Red	[See Intermittent Relay Junction 2]
								Blue w/ White	Blue w/ White	2 (to Lt. Blue Splice B)
								–	–	–
								–	–	–
5	Intermittent Relay Junction 2	Clear	Bullet		Male	1	1	Blue w/ Red		1
6	Body Harness Aux	White	Nylon		Female	6	6	Red w/ Black	Red w/ Black	1
								Red w/ Blue	Red w/ Blue	3 (to Yellow Splice B)
								Yellow w/ Green	Yellow w/ Green	1 (to Lt. Blue Splice A)
								Black	Black	6 (to Yellow Splice F)
								Red w/ Black	Red w/ Black	[See Junction 2A]
								Green w/ White	Green w/ White	2 (to White Splice A)
7	Junction 2A	Clear	Bullet		Male	1	1	Red w/ Black		1
	Light Blue Splice A	N/A	N/A	N/A	N/A	2		Yellow w/ Green		N/A
								Yellow w/ Green
	White Splice A	N/A	N/A	N/A	N/A	2		Green w/ Blue		N/A
								Green w/ White		3 (to White Splice C)
	Light Blue Splice B	N/A	N/A	N/A	N/A	2		Blue w/ White		N/A
								Blue w/ White
	Light Blue Splice C	N/A	N/A	N/A	N/A	2		Black		N/A
								Blue w/ White
	Brown Splice	N/A	N/A	N/A	N/A	2		Red (Thick)		N/A
								Red
	Yellow Splice A	N/A	N/A	N/A	N/A	2		White (Heavy)		N/A
								White
	Yellow Splice B	N/A	N/A	N/A	N/A	3		Red w/ Blue		N/A
								Red w/ Blue
								Red w/ Blue
	White Splice B	N/A	N/A	N/A	N/A	2		Red w/ Blue		N/A
								Green w/ White
8	Radio	White	Nylon		Female	3	2	Red w/ Blue	Red w/ Blue	1 (from White Splice B)
								Black	Black	[See Junction 2B]
9	Junction 2B	Clear	Bullet		Male	1	1	Black		1
10	Radio Illumination / Power - ?	Clear	Bullet		Female	1	1	Blue	Blue	3 (to Yellow Splice D)
11	Fog Light Switch	White	Nylon "T"		Male	2	2	Red	Red	4
								Red w/ Green	Green w/ White	2 (from White Splice B)
12	Fuse Box D	White	Nylon		Male	6	7	Red	Red (Thick)	2 (from Brown Splice)
								Red w/ Yellow	Red w/ Yellow (Thick)	4
								Green w/ Red	Green w/ Red	4
								Green w/ Blue	Green w/ Blue	[See Combinations Switch E]
									Red w/ Blue	4
								Red w/ Blue	Red w/ Blue	2 (from Yellow Splice A)
								Red	Red (Thick)	[See Combinations Switch D]
13	Fuse Box E	Clear	Bullet		Female	1	1	White	White (Thick)	3 (from Yellow Splice A)
14	Glove Box Light	Clear	Bullet		Female	1	1	Red w/ Blue	Red w/ Blue	1 (from Yellow Splice B)
15	Clock Power	Clear	Bullet		Female	1	1	Blue	Blue	1 (to Yellow Splice C)
16	Clock Illumination	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	2 (to Yellow Splice D)
17	Map Light	Clear	Bullet		Female	1	1	Red w/ Blue	Red w/ Blue	1 (to Yellow Splice C)
	White Splice C	N/A	N/A	N/A	N/A	3		Green w/ White		2 (from White Splice B)
								Green w/ White		3 (to White Splice D)
18	Ammeter	Black	Ring w/ Cap (Nylon in FSM)		N/A	1	1	White	White (Heavy)	2 (from Yellow Splice A)
19	Ammeter & Fuel Gauge Illumination	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	2 (to Yellow Splice D)
	Yellow Splice C	N/A	N/A	N/A	N/A	3		Blue		N/A
								Red w/ Blue
								Red w/ Blue
20	Water Temperature & Oil Temperature Gauge Illumination	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	1 (from Yellow Splice D)
	Yellow Splice D	N/A	N/A	N/A	N/A	3		Blue		N/A
								Red w/ Blue
								Red w/ Blue
								Red w/ Blue
21	Tachometer Illumination A	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	2 (to Yellow Splice E)
22	Tachometer Illumination B	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	2 (to Yellow Splice E)
23	Illumination Dimmer (Rheostat)	Black	Spade		Male	1	2	Red w/ Blue	Red w/ Blue	2 (from Yellow Splice D)
									Red w/ Blue	2 (to Yellow Splice E)
		Clear	Spade		Female	1	1	Red w/ Blue	Red w/ Blue	1 (to White Splice D)
24	Cigar & Hazard Fiber Optic Light Source	White	Nylon		Female	2	1		Red w/ Blue	1 (to White Splice D)
									–	–
					Male	1	1		Black	1 (to Cigar Lighter)
	Gray Splice	N/A	N/A	N/A	N/A	3				N/A
	White Splice D	N/A	N/A	N/A	N/A	3		Red w/ Blue		N/A
								Red w/ Blue
								Green w/ White
25	Steering Lock Switch	Clear	Spade		Male	1	1	Black	Black	3 (from Yellow Splice F)
		Clear	Spade		Female	1	1	Red	Red	[See Step Light Harness]
26	Light & Horn Switch	White	Nylon		Female	3	3	Red w/ White	Red w/ White (Thick)	2 (from Gray Splice)
								Red w/ Black	Red w/ Black	6
								Green w/ Black	Green w/ Black	6
27	Combinations Switch D	Clear	Bullet		Male	1	1	Red	Red (Thick)	6
28	Combinations Switch E	White	Nylon		Female	9	9	Blue w/ Yellow	Blue w/ Yellow	6
								Blue	Blue	7
								Blue w/ Red	Blue w/ Red	[See Junction 2C]
								Yellow w/ Black	Yellow w/ Black	6
								Red w/ Blue	Red w/ Blue	6
								Blue w/ White	Blue w/ White	6 (from Lt. Blue Splice C)
								Blue w/ White	Blue w/ White	6 (from Lt. Blue Splice B)
								Green w/ Blue	Green w/ Blue	6
								Green w/ White	Green w/ White	2
29	Junction 2C	Clear	Bullet		Male	1	1	Blue w/ Red		1
	Yellow Splice E	N/A	N/A	N/A	N/A	3		Red w/ Blue		N/A
								Red w/ Blue
								Red w/ Blue
	Yellow Splice F	N/A	N/A	N/A	N/A	2		Red w/ Blue		N/A
								Red
	Yellow Splice G	N/A	N/A	N/A	N/A	2		Black		N/A
								Black
30	Speedometer Illumination Top	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	1 (from Yellow Splice F)
31	High Beam Indicator Light	Black	Bulb		N/A	1	2	Red	Red	4 (to Brown Splice)
								Red w/ White	Red w/ White	2 (from Gray Splice)
32	Speedometer Illumination Bottom	Black	Bulb		N/A	1	1	Red w/ Blue	Red w/ Blue	2 (from Yellow Splice E)
33	Hand Brake Junction	Clear	Bullet		Male	1	1	Yellow w/ Green		6 (from Lt. Blue Splice A)
34	Step Light Harness	Clear	Bullet		Male	1	1	Black	Black	1 (from Yellow Splice G)
		Clear	Bullet		Female	1	1	Red w/ Blue	Red w/ Blue	1 (from Yellow Splice F)
35	Door Switch LH	Clear	Bullet		Female	1	1	Black	Black	1 (from Yellow Splice G)
		Clear	Spade		Female	1	1	Black	Black	3

Edited August 26, 2022 by Matthew Abate

[Matthew Abate]

I did a quick tally of which wires need to be which gauge and this is what I ended up with:

Components	Gauge	Wire Color
Starter Ground, Combination Switch	10	Black
		Black w/ White
Fuel Pump		Green
Headlights		Red w/ White
Starter, Ammeter		White
Alternator, Ammeter		White w/ Red
	12	Black w/ White
Ignition Switch		Black w/ Yellow
Ignition Switch		Green w/ White
Headlights, Combination Switch		Red
Rear Glass Defroster		Red w/ Black
Light & Horn Switch		Red w/ White
Headlights		Red w/ Yellow
Fuse Box		White
Ignition Switch, Combination Switch		White w/ Red

All others would be 14 AWG. There may be some 16 or 18 AWG in the car originally, but I don't see a reason to go that light. Please let me know if you think I have any errors here. I'm also wondering if it would be worthwhile to step everything up one level, or if that would be a waste of money and weight.

Edited September 4, 2022 by Matthew Abate

[SteveJ]

Just be aware of what gauge wires your terminals are designed to take. 

Doing some quick resistance calculations, you are upsizing a lot of wires with little to no benefit. You may end up with an issue getting your engine harness through the hole in the firewall. (Keep in mind that it will probably be easier if you put the pins in the connectors after you get the harness through the firewall.) 

You may want to check out a voltage drop calculator like this: https://www.calculator.net/voltage-drop-calculator.html

Choose estimated resistance. I did a quick calculation for the headlights with a swag for the distance and used incandescent sealed beam ratings. The voltage is 13.8 because that is toward the low end of operating voltage while the car is driving.

Many of your circuits for the engine harness are grounded close to the load, so this calculator would overestimate the voltage drop. 

The battery/charging system are your highest current circuits, so the larger gauge can easily be justified. No other circuit comes close especially if you change the parking light circuit to LEDs, as that is probably the biggest continuous draw you would see.

Other high draw circuits:

Fan (14 AWG is fine, but you might be better off with 12 AWG)

Fuel pump (This is about 10 A or less. 14 AWG would work.)

Headlights (depending upon whether or not you switch to LEDs. LEDs would drop this circuit to about 3 A.)

Edited September 4, 2022 by SteveJ
Fixing grammar

[Matthew Abate]

I plan to use LEDs but I want to wire the car so that I don’t HAVE to use LEDs, particularly for the headlights.

My thoughts on having 14 AWG be my smallest wire was coming from a few things:

First, the amount of fried wiring I found. It’s possible the heat came from outside but in places like under the dash I don’t know what would cause that, so I was assuming that it was overload on the wiring.

Second, the general use of 10-amp fuses for everything that wasn’t one of the fatter wires, plus the gauge charts I’ve been using. However, I suspect the dash maybe could come down a notch for all the instruments and save me some headaches with fitting all that stuff in there.

Third, just eyeballing stuff looks like a lot of 14 AWG. Maybe I’m off base and It's smaller than that. Tough to tell since it's actually Japanese (square millimeter?) wire and not AWG. need to go back over it more carefully.

I would love to plug all the numbers for everything in the car into a calculator, but I just don’t know where to find that information.

Edited September 4, 2022 by Matthew Abate