1973 240z Automatic to Manual Questions

[Matthew Abate]

I have been working on creating a comprehensive diagrams so I can rebuild all of my wiring and I could really use some help with the last couple of details.

Context: The previous owner sold me the car largely disassembled so I have had to chase all of the wires and connectors and figure out what they go to. In the process of doing that I discovered that my engine harness is for an automatic, but I have a manual car. There are also a couple of wires that were snipped.

The first thing I need to understand is what one of the cut wires is for. It's a thin black wire (approximately 14 or 16 AWG) and comes out of the main trunk of the harness near the Seatbelt Relay connector. I traced it to the top left pin in the green connector (15B on page BE-2 of the FSM), which corresponds to a wire that is missing on my dashboard harness. This makes me think these wires are dedicated to the automatic cars.

 

The next thing I need to understand is how the manual harness is different from the automatic harness for this year. I already figured out how the throttle opener solenoid wires are different, but I could use help with understanding the wires that go to the 4-pin connector that replaces the 6-pin connector for the seatbelt relay.

The 6-pin connector wires are BY, BY, BY, B, G, G (#17 on page BE-2 in the FSM) and the wires for the 4-pin connector are GB, BW, BW, BY (#18 on page BE-2 of the FSM). I am pretty sure the GB wire on the manual is for the throttle opener solenoid and connects to the speed switch on the speedometer. I assume the BY wire on the manual replaces the third BY on the automatic. I have no idea about the others. I would have assumed there was a green on in there but no.

The last thing I need to figure out is what the BY wire on the blue connector goes to. It's the center pin on the bottom (#15-A on page BE-2 of the FSM). This is completely missing on my engine harness, but also on my dashboard harness, which leads me to believe it is specific to manual cars, just like the GB wite for the throttle opener.

 

I would really appreciate help ironing these details out. It's the final roadblock on getting my wiring diagram done so I can start rebuilding it. Let me know if are details I should add that would help.

Edited February 15, 2023 by Matthew Abate

[Zed Head]

Maybe the full wiring diagram would help.  EuroDat put a few colored versions together.

https://www.classiczcars.com/files/category/1-wiring-diagrams/

[SteveJ]

32 minutes ago, Matthew Abate said:

I have been working on creating a comprehensive diagrams so I can rebuild all of my wiring and I could really use some help with the last couple of details.

Context: The previous owner sold me the car largely disassembled so I have had to chase all of the wires and connectors and figure out what they go to. In the process of doing that I discovered that my engine harness is for an automatic, but I have a manual car. There are also a couple of wires that were snipped.

The first thing I need to understand is what one of the cut wires is for. It's a thin black wire (approximately 14 or 16 AWG) and comes out of the main trunk of the harness near the Seatbelt Relay connector. I traced it to the top left pin in the green connector (15B on page BE-2 of the FSM), which corresponds to a wire that is missing on my dashboard harness. This makes me think these wires are dedicated to the automatic cars.

On my spare dash harness, it's another case of the FSM not matching. Looking at the back side of the connector, here is the wiring:

The green wires are probably for the seat belt buzzers. 

48 minutes ago, Matthew Abate said:

The next thing I need to understand is how the manual harness is different from the automatic harness for this year. I already figured out how the throttle opener solenoid wires are different, but I could use help with understanding the wires that go to the 4-pin connector that replaces the 6-pin connector for the seatbelt relay.

The 6-pin connector wires are BY, BY, BY, B, G, G (#17 on page BE-2 in the FSM) and the wires for the 4-pin connector are GB, BW, BW, BY (#18 on page BE-2 of the FSM). I am pretty sure the GB wire on the manual is for the throttle opener solenoid and connects to the speed switch on the speedometer. I assume the BY wire on the manual replaces the third BY on the automatic. I have no idea about the others. I would have assumed there was a green on in there but no.

The seat belt relay does not exist in the manual. The green wires go to the neutral switch on the transmission. I think when the car is in gear, the neutral switch completes the circuit to go to the buzzer and seat belt light if you don't have the belts fastened in occupied seats. (Be sure to buckle in your groceries if you put them in the passenger seat.)

I think you and I discussed the throttle opener in a private message. In the engine bay, the BW wire splits to go to both BW terminals on connector 18. The BY goes to the throttle opener solenoid, and GB goes to the speedometer.

49 minutes ago, Matthew Abate said:

The last thing I need to figure out is what the BY wire on the blue connector goes to. It's the center pin on the bottom (#15-A on page BE-2 of the FSM).

 

 

 

I would really appreciate help ironing these details out. It's the final roadblock on getting my wiring diagram done so I can start rebuilding it. Let me know if are details I should add that would help.

So for this one, the LY wire is NOT LY. It is LW. I used a meter on my spare harness to find where it goes. It's part of the wiper circuit, going to the 9 pin connector at the steering column and the 6 pin connector at the intermittent relay.

Here is the layout of the blue connector on my harness:

[Matthew Abate]

On 2/15/2023 at 6:31 PM, Zed Head said:

Maybe the full wiring diagram would help.  EuroDat put a few colored versions together.

https://www.classiczcars.com/files/category/1-wiring-diagrams/

Thanks, but the full diagram from Eurodat is what I started with. These specific things aren't covered in it.

 

Here is a drawing showing how the wires in my harness are routed from the green connector to the seatbelt switch:

 

Notice that I have two BY wires going to my neutral switch, not green, and they come out of the seatbelt switch, not the green connector. If I understand you correctly, on the manual cars the green wires bypass the 4-pin connector and go straight to the neutral safety switch. Now that I think about it, the inhibitor switch on automatic cars replaces the neutral safety switch, so I have a flaw in my diagram for that.

@SteveJ what does the 4-pin connector plug into since there’s no seatbelt relay? I am assuming the green connector's BY wire and GB wire (marked as missing in the drawing above) go to that 4-pin connector. If the BW wires merge somewhere into one wire I have no idea where that BW wire would come from.

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And it sounds like that BY wire on the blue connector I was asking about just isn’t really there since neither of us have it on our harnesses.

Edited February 17, 2023 by Matthew Abate

[SteveJ]

So the connector you're talking about is on the engine harness. My "spare" isn't in a decent condition to analyze. I may be able to see it in my car. I'll try to remember, but it may take some gentle nudging.

 

[Matthew Abate]

14 hours ago, SteveJ said:

So the connector you're talking about is on the engine harness. My "spare" isn't in a decent condition to analyze. I may be able to see it in my car. I'll try to remember, but it may take some gentle nudging.

 

Yeah, the connector I am looking for information on is the one on the Engine harness labeled 18 in the FSM. It should be in the same position on the manual harness as the Seatbelt relay on the Automatic harness, based on what is in the FSM illustration.

I need to know what it connects to and where the two BW wires are coming from. If possible, I would love to know whether any of the four wires in that connector are spliced to something else, but I understand that is a long shot request.

[Matthew Abate]

@SteveJ I have a theory:

I am guessing that the two G wires that go into the 6-pin connector on an automatic are the ones that go to the neutral safety switch on a manual.

I am also guessing that the BY wire coming off the orange splice is one of the two BW wires on your manual that goes to the 4-pin connector. On my harness that BY wire splices to wires terminating at the coil positive, the fuse box, the front electric fuel pump, The ignition switch, and the throttle opener switch.

I believe the GB wire comes off the green connector and ends up in that 4-pin connector somehow (either directly or via a splice).

If all of this is correct, then this should be right:

 

It would look like this in my diagram:

 

We just need to figure out whats up with those BW wires.

 

Edited February 17, 2023 by Matthew Abate

[SteveJ]

I knew I had looked at this before. 

That connector resides here

Here it is in the wiring diagram. While it's on the passenger side firewall, the diagram has it by the coil.

It hints that the BW wire spits before the 4 pin connector, but I'm not sure we can believe that. The BY wire would go from the passenger firewall, around the front of the engine, and over to the intake.

The GB wire changes color somewhere and goes to the relay on the speedometer where it gets grounded. I think you and I discussed that in emails. The "green" wire in the wiring diagram changes color before that connector, too.

 

Edited February 18, 2023 by SteveJ

[Matthew Abate]

Aha! Wonderfull. Thanks @SteveJ.

The 4-pin connector goes to the Throttle Opener Relay. That explains why I couldn't figure it out. It also means that I am SOL since you can't get them anymore. It also means that I am 100% going to delete that from my system and go with a Fast Idle Control Device to prevent the engine from being bogged down when I turn on the AC. I know they serve different purposes, but that's my plan.

Regardless, the way I have it drawn up is definitely wrong. I'm pretty sure the BY wire goes to the opener solenoid and is not the one coming from the green connector. I would like to update the diagram I have been making to cover this stuff so that I can make it available for everyone if they want it. I will send you a draft. Maybe you can fill in the blanks on that one bit.

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Regarding the GB wire changing color to YR, I have identified that change as happening at the colored connectors on my harnesses. I have a YR wire that goes all the way from the speed switch on the back of the speedometer to the green connector on the dashboard harness without interruption. That pin corresponds to the GB wire on the green connector of the manual engine harness. This is backed up by the illustration 15-B on page BE-2 and illustration 8-B on page BE-3 in the 1973 FSM, which doesn't confirm that I'm correct but does point that way.

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The last little detail is the black wire on the green connector that I asked about earlier. There are two black wires on that connector and the one I can't figure out is the thinner one. Right now I have it as going to the accessory wire on the negative cable coming off the battery, but I am not confident about that at all.

Edited February 18, 2023 by Matthew Abate

[Diseazd]

I’m not much on electrical issues (I leave that up to Steve), but when I swapped a manual into my automatic 73, all I did was join the two park lock-out wires at the tranny together and was good to go. The throttle linkage out of the firewall was another small issue, but easy to solve.