1973 240z Custom Wiring From Scratch

[SteveJ]

39 minutes ago, Matthew Abate said:

• I have a yellow wire ending in a female bullet connector sharing a sleeve with a black wire ending in a female spade connector
• That black wire extends to where the yellow wire merges into the harness and has another female spade connector
• At that same point I have a green w/ white wire and a black w/ white wire, both ending in female spade connectors
• There is also a longer black w/ white wire ending in a female spade connector and shrouded in a black sleeve

Yellow - connects to the temp sender

Black - goes from the distributor to coil negative

Green/white - from ballast resistor to tachometer

Black/white - from key switch (ignition power) to ballast resistor

Black/white with shroud - from tachometer to coil positive

44 minutes ago, Matthew Abate said:

Further up the harness, about 10 inches from the bundle of wires for the lights on the left side of the car, I have 3 wires that have been cut: black w/ yellow, green, and black. See the far left side of the following image.

Black/yellow & black - washer motor

Green - typically horn

58 minutes ago, Matthew Abate said:

The next mystery is a bundle of 4 wires that emerges between the bundle for the starter and the thick branch of wires that holds the wiper motor connector, among others. There are 2 red w/ black ending in male bullet connectors and 2 black w/ yellow ending in female bullet connectors. See the middle of the image below

Red/black - reverse light switch on transmission

Black/yellow - neutral safety switch for solenoid power

1 hour ago, Matthew Abate said:

Lastly, I have two 4 wires emerging from that thick branch that holds the wiper motor connector and what I think is the seatbelt relay (automatic only). There is a black wire that is on its own and has been cut. There is also a bundle of 3 wires: black ending in a male spade connector, black w/ yellow ending in a female spade connector, and yellow with green ending in a female bullet connector. This bundle of wires is about 6 1/2 feet long, and the diagram does not show any yellow w/ green wires.

The black was probably a ground - maybe the chassis ground?

Black/yellow - solenoid power

Yellow/green - not sure why this would be alone. It could be associated with the intermittent wiper relay. Page BE-2 does show the Y/G wire as a pin on a 3 wire connector. The mystery is that BE-2 shows 2 Y/G wires for the engine harness. One is on the blue connector, and the other is on the white connector. However, I only can find the destination of one Y/G wire at the 3 wire connector.

[Matthew Abate]

Thanks @stevej!

Some of this is definitely right, but I have some questions about a few things.

8 hours ago, SteveJ said:

Black/yellow & black - washer motor

Green - typically horn

Is the washer motor not up on the washer tank by the firewall? If it is, I think we both has some stuff swapped around.

I thought maybe these wires went to the Thermo Switch and other things that connected to the distributor on the Automatic cars. Here's a close crop of the illustration in the FSM where this stuff is. It would be between the lights and the ballast resistor, but I don't see a branch in the harness in the illustration.

I'm pretty sure I have the green wires for the horns accounted for in the bundles coming out of the loom near the headlights. This one is further down the harness toward the coil. I chased it back to a splice where it joins a green wire that goes back to the other end. There are two black w/ white wires in that splice as well. These are the ones that go to the coil and stuff you mentioned.

 

8 hours ago, SteveJ said:

The black was probably a ground - maybe the chassis ground?

There is a black wire running to a ground next to the battery in the wiring diagram. Do you think it's this one? (Why the hell would someone cut that!?!)

 

8 hours ago, SteveJ said:

Yellow/green - not sure why this would be alone. It could be associated with the intermittent wiper relay. Page BE-2 does show the Y/G wire as a pin on a 3 wire connector. The mystery is that BE-2 shows 2 Y/G wires for the engine harness. One is on the blue connector, and the other is on the white connector. However, I only can find the destination of one Y/G wire at the 3 wire connector.

I am wondering if this whole mess actually goes to the washer tank and what I have labeled as the washer tank wire goes somewhere else. Here's where this is in the FSM illustration:

It would make sense that this thin branch would be this part given how long it is. However, if it is some of these other things are not what I have them labeled now.

Edited June 29, 2022 by Matthew Abate

[SteveJ]

Okay, so I went down to my car to take a look to see what I could match up. The black/yellow and green wire are for emissions controls. Matching wire lengths helps, even if the controls have been removed.

The black/yellow is for the opener control valve, and the green is for the solenoid valve. Look through the EC section of the FSM for more info. In my car, a previous owner had cut the wires and spliced them back in. I'm not sure why.

In looking at the washer motor, my car does not have a yellow/green running to the washer motor. I believe it was black/yellow. I could not find a single yellow/green, only the one in the 3 wire connector for the wiper amplifier. Of course, there's only so much time I'll spend contorted in the footwell to look at the wiring. 

As for why someone would cut off a body ground...well, I don't use the term IPO (idiot previous owner) for fun.

[SteveJ]

So I did a little more digging. The black/yellow is shown toward the bottom left of the wiring diagram.

This shows the green wire. There might be a black/white wire hiding around there, too.

 

[Matthew Abate]

Thank you for getting in there and checking! I’ll take this back and start chasing the wires to see where things connect on the other end. Maybe that will clear it up.

[Matthew Abate]

I think I found the answer to the yellow w/ green wire question: apparently it's from a low brake fluid/pressure sensor to the e-brake light on the dash.

 

Edited July 1, 2022 by Matthew Abate

[SteveJ]

I went to my car to verify and cleaned up the wire. Confirmed! Good sleuthing!

[Matthew Abate]

It's labeled "Brake ind." in the diagram and the wire shown is yellow with blue. It's also Yellow w/ Blue on pages BE-5 and BE-6 in the FSM diagram, conflicting with page BE-2.

Edited July 1, 2022 by Matthew Abate

[SteveJ]

The interesting thing is the wiring diagram lists it as yellow/blue. The stripe sure looks green to me. Maybe it just really faded.

[Matthew Abate]

I have another table for you, this time for the engine harness in automatic cars.

For manual cars, you would not have the Seatbelt Relay, the Inhibitor Switch, the Thermo Relay, or the Thermo Switch. In a 1973 car with a manual transmission, you WOULD have the Throttle Opener Vacuum Relay for the flat top carburetors (not included in the table).

Note that there are a few things I was unsure of in here, so they are marked with a pink background in the table cell. The wires that were cut have indeterminant lengths, so I measured how long they were to the point where they were cut. Where the harness I have differs from the FSM and wiring diagrams, I have marked the change in red.

The things I am most curious / worried about are the missing black w/ yellow wire that should be coming out of the blue 10-pin connector and the missing green w/ black wire that should be coming out of the green 10-pin connector.

1973 240z Engine Harness (Automatic Transmission) 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	Instrument Harness A	Blue	10-Prong		F	10	9	Red w/ Black	Red w/ Black	6 (to Yellow Splice C)
								Red w/ White	Red w/ White (Heavy)	[See Headlight LH]
								Green w/ Black	Green w/ Black	[See Horn Relay]
								Green w/ Red	Green w/ Red	[See Horn Relay]
								–	–	–
								Yellow w/ Green	Yellow w/ Green	[See Low Brake Fluid/Pressure Sensor]
								Red w/ Black	Red w/ Black	[See Reverse Light Switch on Trans]
								Black w/ Yellow	–	?
								Red	Red	[See Fog Light RH]
								Blue w/ Yellow	Blue w/ White	[See Wiper Motor]
	Instrument Harness B	Green	10-Prong		F	10	8	Black	Black	[See Ground - ?]
								Black	Black (Heavy)	2 (to Blue Splice A)
								Green w/ Black	–	?
								–	–	–
								–	–	–
								Green w/ Black	Green w/ Black	[See Parking & T/S & Side Front RH]
								Green w/ Red	Green w/ Red	[See Parking & T/S & Side Front LH]
								Blue	Black w/ Yellow	[See Seat Belt Relay]
								Green	Green	[See Seat Belt Relay]
								Green	Green	[See Seat Belt Relay]
	Instrument Harness C	White Black	10-Prong		F	10	8	Blue w/ Yellow	Blue w/ Yellow	[See Wiper Motor]
								Red	Red (Thick)	[See Headlight RH]
								Green w/ Blue	Green w/ Blue	5 (to Blue Splice F)
								Red w/ Blue	Red w/ Blue	[See Inspection Light]
								Red w/ Yellow	Red w/ Yellow (Thick)	[See Headlight LH]
								–	–	–
								–	–	–
								Black	Black	[See Water Tank]
								Blue	Blue	[See Wiper Motor]
								Yellow w/ Green	Yellow w/ Green	[See Intermittent Relay]
	Instrument Harness D	Black White	10-Prong		F	10	9	Blue w/ Red	Blue w/ Red	2 (to Yellow Splice A)
								Yellow w/ Black	Yellow w/ Black	[See Oil Pressure Switch]
								Black w/ White	Black w/ White	2 (to Orange Splice A)
								Black w/ White	Black w/ White	4 (to Blue Splice C)
								Yellow w/ White	Yellow w/ White	[See Temperature Sending Sensor]
								–	–	–
								Green	Green	[See Hazard]
								White	White	[See Hazard]
								Black w/ White	Black	[See Ballast Resistor]
								Green w/ White	Green w/ White	[See Ballast Resistor]
	Instrument Harness E	White				1	1	White w/ Red	White w/ Red (Heavy)	[See Alternator]
	Instrument Harness F	White				1	1	White	White (Heavy)	3 (to Green Splice A)
	Horn Relay	Clear	Spade		F	1	1	Green w/ Black	Green w/ Black	2
		Clear	Spade		F	1	1	Green	Green	7 (to Yellow Splice D)
		Clear	Spade		F	1	1	Green w/ Red	Green w/ Red	2
	Intermittent Relay	White	4-Prong		F	4	3	Yellow	Yellow	[See Wiper Motor]
								Green	Black	4 (to Blue Splice B)
								Yellow w/ Green	Yellow w/ Green	2
	Hazard	White	2-Prong (90 Degree)		F	2	2	White	White	2
								Green	Green	2
	Yellow Splice A	N/A	N/A	N/A	N/A	2	2	Blue w/ Red		N/A
								Red w/ Black
2	Seatbelt Relay (A/T)	White	4-Prong		F	6	6	Black w/ Yellow	Black w/ Yellow	[See Neutral Safety Switch]
								Black w/ Yellow	Black w/ Yellow	6 (to Yellow Splice C)
								Black w/ Yellow	Black w/ Yellow	[See Inhibitor Switch]
								Black	Black	1 (to Blue Splice A)
								Green	Green	3
								Green	Green	3
	Wiper Motor	White	6-Prong		F	6	5	Blue w/ White	Blue w/ White	4
								Blue	Blue	4
								Blue w/ Yellow	Blue w/ Yellow	4
								Yellow	Yellow	4
								Black	Black	2 (to Blue Splice A)
								Blue w/ Red	Blue w/ Red	2 (from Yellow Splice A)
	Ground - ?			Missing		1	1		Black	4+ (from Blue Splice A)
	Water Tank	Clear	Spade		F	1	1	Black w/ Yellow	Black w/ Yellow	8
		Black	Spade		M	1	1	Black	Black	8
	Low Brake Fluid/Pressure Sensor	Clear	Bullet (Large)		F	1	1	Yellow w/ Green	Yellow w/ Green	9
	Yellow Splice B	N/A	N/A	N/A	N/A	2	2	Black w/ Yellow		N/A
								Black w/ Yellow
	Orange Splice A	N/A	N/A	N/A	N/A	2	2	Black w/ White		N/A
								Black w/ Yellow
	Blue Splice A	N/A	N/A	N/A	N/A	3	3	Black		N/A
								Black
								Black (Heavy)		2 (to Blue Splice B)
3	Reverse Light Switch on Trans	Clear	Bullet		M	1	1	Red w/ Black	Red w/ Black	4
		Clear	Bullet		M	1	1	Red	Red w/ Black	3 (from Yellow Splice A)
	Neutral Safety Switch (for solenoid power)	Clear	Bullet		F	1	1	Black w/ Yellow	Black w/ Yellow	5
		Clear	Bullet		F	1	1	Black w/ Yellow	Black w/ Yellow	5
	Blue Splice B	N/A	N/A	N/A	N/A	3	3	Black		N/A
								Black (Heavy)
								Black (Heavy)		2 (to Blue Splice C)
	Blue Splice C	N/A	N/A	N/A	N/A	3	3	Black w/ White		N/A
								Black w/ White
								Green
	Green Splice A	N/A	N/A	N/A	N/A	2	2	White (Heavy)		N/A
								White
4	Starter Motor	White	1-Prong		M	1	1	White	White (Heavy)	1 (from Green Splice A)
	Starter Ground	Black	Ring		N/A	1	1	Black	Black (Heavy)	2 (from Blue Splice B)
	Inhibitor Switch (A/T)	Clear	Spade		F	1	1	Black w/ Yellow	Black w/ Yellow	4
	Blue Splice D	N/A	N/A	N/A	N/A	3	3	Black		N/A
								Black (Heavy)
								Black (Heavy)
6	Oil Pressure Switch					1		Yellow w/ Black	Yellow w/ Black	6
	Alternator	White	2-Prong		F	2	2	White w/ Black	White w/ Black	5
								Yellow	Yellow	[See Voltage Regulator]
		Black	Ring w/ Cap		N/A	1	1	White w/ Red	White w/ Red (Heavy)	5
	Alternator Ground	Black	Ring		N/A	1	1	Black	Black (Heavy)	2 (from Blue Splice B)
7	Voltage Regulator	White	6-Prong		F	6	5	Yellow	Yellow	2
								White	White	5
								Black	Black	5
								White w/ Black	White w/ Black	5
								Black w/ White	Black w/ White	5
	Distributor Condenser	Clear	Bullet		F	1	1	Black w/ White	Black w/ White	5
5	Inspection Light	Clear	Bullet		F	1	1	Red w/ Blue	Red w/ Blue	7
	Blue Splice E	N/A	N/A	N/A	N/A	2	2	Black		N/A
								Black		2 (from Blue Splice D)
	Yellow Splice C	N/A	N/A	N/A	N/A	2	2	Red w/ Black		N/A
								Red w/ Black
	Blue Splice F	N/A	N/A	N/A	N/A	2	2	Green w/ Blue		N/A
								Green w/ Blue
	Yellow Splice D	N/A	N/A	N/A	N/A	2	2	Green		N/A
								Green
	Orange Splice B	N/A	N/A	N/A	N/A	2	2	Red w/ White (Heavy		N/A
								Red w/ Black (Thick)
8	Side Marker Lamp RH	Clear	Bullet		F	1	1	Green w/ Blue	Green w/ Blue	2 (from Blue Splice F)
		Clear	Bullet		M	1	1	Black	Black	2 (from Blue Splice E)
	Parking & T/S & Side Front RH	White	3-Prong		F	3	5	Black	Black	6
									Black	6
								Green w/ Blue	Green w/ Blue	2 (from Blue Splice F)
									Green w/ Blue	2 (to Blue Splice G)
								Green w/ Black	Green w/ Black	6
	Head Light RH	White	3-Prong		M	3	3	Red	Red (Thick)	6
								Red w/ Black	Red w/ Black	6
								Red w/ White	Red w/ Black	1 (from Yellow Splice C)
	Fog Light RH	Clear	Bullet		M	1	1	Black	Black	6
		Clear	Bullet		F	1	2	Red	Red	[See Fog Light LH]
										6
	Horn RH	Clear	Spade		F	1	1	Green	Green	6
	Blue Splice G	N/A	N/A	N/A	N/A	2	2	Green w/ Blue		N/A
								Green w/ Blue
	Blue Splice H	N/A	N/A	N/A	N/A	2	2	Black		N/A
								Black
9	Horn LH	Clear	Spade		F	1	1	Green	Green	8
	Fog Light LH	Clear	Bullet		M	1	1	Black	Black	8
		Clear	Bullet		F	1	1	Red	Red	8
	Parking & T/S & Side Front LH	White	3-Prong		F	3	3	Black	Black	8
								Green w/ Red	Green w/ Red	8
								Green w/ Blue	Green w/ Blue	1 (from Blue Splice G)
	Head Light LH	White	3-Prong		M	3	3	Red w/ Yellow	Red w/ Yellow	8
								Red w/ White	Red w/ White (Heavy)	8
								Red w/ Black	Red w/ Black	3 (to Yellow Splice C)
	Side Marker Lamp LH	Clear	Bullet		F	1	1	Black	Black	8
		Clear	Bullet		M	1	1	Green w/ Blue	Green w/ Blue	1 (from Blue Splice G)
10	Thermo Switch (A/T) - ?			Missing			1		Black w/ Yellow	7+ (from Yellow Splice B)
	Thermo Relay (A/T)			Missing			1	Black	Black	9+
				Missing			1	Green	Green	9+
11	Temperature Sending Sensor	Clear	Bullet		F	1	1	Yellow w/ White	Yellow w/ White	13
	Distributor	Clear	Spade		F	1	1	Black	Black	[See Coil]
	Coil Positive	Clear	Spade		F	1	1	Black w/ White (w/ Shroud)	Black w/ White (w/ Shroud)	12 (from Orange Splice A)
	Coil Negative	Clear	Spade		F	1	1	Black	Black	2
	Balast Resistor	Clear	Spade		F	1	1	Green w/ White	Green w/ White	12
		Clear	Spade		F	1	1	Black w/ White	Black w/ White	12

Edited July 12, 2022 by Matthew Abate

[Patcon]

I love this table! I would love to see a hardware table like this for the 240z with pictures of the fasteners beside the descriptions

[Matthew Abate]

Thanks! I am hopeful that I didn't make any errors. If I did it would most likely be with the measurements of the wire lengths, since I was super tired of working on this harness by the time I got to that step. I checked them a couple of times, so they should be right, but there are a lot more splices in this harness than there were in the body harness and they are mostly blue or yellow, so difficult to keep straight.

I'm also bothered by the fact that someone cut 4 of the wires and I can't tell you how long they should be or what the connector should be. :/

–––

Also, I was wondering if anyone knows what gauges the OEM wires are. It looks like there are 3, maybe 4 sizes, which I have tried to indicate with (heavy) and (thick) next to the wire colors in the table.

Edited July 10, 2022 by Matthew Abate