Duffy's 1/71 Series 1 240z build

[duffymahoney]

34 minutes ago, SteveJ said:

As designed by Nissan, the BW wire from the ignition switch is not the primary source for power to the coil while cranking. The GW (or GL depending upon the drawing) wire is. The reason is that the GW gives a hotter spark while starting, but in normal operation, the BW wire runs through the ballast resistor to drop the voltage to reduce the wear on the points. 

Very cool, I didn't know the ballasts design.  That makes total sense! 

[SteveJ]

12 minutes ago, duffymahoney said:

Very cool, I didn't know the ballasts design.  That makes total sense! 

If you spend too much time on this board, like I do, you learn things like that. I try to absorb as much as possible from the smart people here.

[duffymahoney]

I am waiting on the stock style terminals to finish it, but I still think the switch is to blame.  Which sucks.  

[Zed Head]

44 minutes ago, duffymahoney said:

I am waiting on the stock style terminals to finish it, but I still think the switch is to blame.  Which sucks.  

The ignition switch is very simple.  You could just measure continuity through the pins on the back and determine if it's bad.  The pins are marked.

[jfa.series1]

3 hours ago, SteveJ said:

I don't disagree with you except to say it's not a small point. I would say it's a moderately sized point. 

It would be great if someone with an earlier car could confirm how the "single screw" switch operates electrically. It's pretty easy, as I mentioned before. Take the BY off the solenoid, switch the turn signal switch to left or right, and put the key in start. If the turn signals flash, the BW wire is powered during start.

@jfa.series1 Does your car have an original switch?

While the electrical component of my ignition switch has been replaced twice over the years I still have the OE mechanical part of it. Let me know what you are looking for.

[duffymahoney]

Yeah I should do that! I'm 99% sure it's the switch, since I could see it happen on my multi meter. 

[SteveJ]

25 minutes ago, jfa.series1 said:

While the electrical component of my ignition switch has been replaced twice over the years I still have the OE mechanical part of it. Let me know what you are looking for.

I'm thinking that if you replaced the electrical component, the replacement may have design changes from the original. 

Unfortunately it's a part that sees a lot of use over the lifespan of the car, so finding a completely original switch on an early car could be a challenge.

This really doesn't go to solve Duffy's issue. It's really just to validate the wiring drawings, so I should make a separate thread for this rabbit hole.

[Zed Head]

I had a switch on a 78 parts car with a loose S pin.  The staked area had loosened.  I rapped it a couple of times with a chisel and fixed it.  

Edited August 23, 2022 by Zed Head
come loose? become loose? > loosened

[Captain Obvious]

And just so I'm positive that I wasn't seeing things, here's a couple threads that talk about the old one eared ignition switch:

https://www.classiczcars.com/forums/topic/45631-ignition-switch/

https://www.classiczcars.com/forums/topic/49960-240z-ignition-problem/

Good pics in those threads. Like this one:

 

So it's completely conceivable that those older one-eared switches did not follow the same power map as the newer two-eared versions, but without a sample, I'm not sure if we will be able to figure out if that's the case, or if it's a documentation error.

Me personally? I find it really odd that they would kill the power to the ballast resistor while in the START position. I would expect them to keep that powered in both ON and START. You need a bump-less transfer between those two when you are starting the car. You don't want a dead spot between those two positions.

 

Edited August 24, 2022 by Captain Obvious
more detail

[duffymahoney]

13 hours ago, Captain Obvious said:

And just so I'm positive that I wasn't seeing things, here's a couple threads that talk about the old one eared ignition switch:

https://www.classiczcars.com/forums/topic/45631-ignition-switch/

https://www.classiczcars.com/forums/topic/49960-240z-ignition-problem/

Good pics in those threads. Like this one:

 

So it's completely conceivable that those older one-eared switches did not follow the same power map as the newer two-eared versions, but without a sample, I'm not sure if we will be able to figure out if that's the case, or if it's a documentation error.

Me personally? I find it really odd that they would kill the power to the ballast resistor while in the START position. I would expect them to keep that powered in both ON and START. You need a bump-less transfer between those two when you are starting the car. You don't want a dead spot between those two positions.

 

I will test mine when I get it! I would guess it would have power in the start position.  

[SteveJ]

14 hours ago, Captain Obvious said:

And just so I'm positive that I wasn't seeing things, here's a couple threads that talk about the old one eared ignition switch:

https://www.classiczcars.com/forums/topic/45631-ignition-switch/

https://www.classiczcars.com/forums/topic/49960-240z-ignition-problem/

Good pics in those threads. Like this one:
 

 

So it's completely conceivable that those older one-eared switches did not follow the same power map as the newer two-eared versions, but without a sample, I'm not sure if we will be able to figure out if that's the case, or if it's a documentation error.

Me personally? I find it really odd that they would kill the power to the ballast resistor while in the START position. I would expect them to keep that powered in both ON and START. You need a bump-less transfer between those two when you are starting the car. You don't want a dead spot between those two positions.

 

It is an interesting mystery. The wiring diagram was probably done well after the parts were designed, so it's not surprising. Humans were involved, and they didn't have the neat CAD software available to fix their mistakes quickly. Just today I noticed an anomaly in the wiring diagram for the intermittent relay in the 73. 

I would need to hook up my oscilloscope to see if the transfer is truly bumpless between start and on for the IG terminal on the switch. I don't think it is, but with the inertia of the engine once it fires, it could handle the very short gap in time.

[Zed Head]

Do you really need a scope?  A slow turn of the switch and a meter should tell the story.  It would have to be controlled by the width of the moving contact.  If it bridges On and Start it's "bumpless", if it doesn't there's a bump.  p.s. the bridging would be only at the "between" point.  Not when it was fully to the Start position.

It might be in one of CO's links but I remember people having problems with their Haltechs or other EFI systems losing communication from Start to On or vice-versa.  The computer resets and it causes problems.  Can't remember what the cause or solution was though.

Edited August 24, 2022 by Zed Head