510, Apparent soft short, expertise, and gerenal thoughts please

[BZT8FS]

Wow! Thanks everybody, I really appreciate the support!
 - banzai510(hainz) - not measuring through the flasher, just the turn signal switch, completely disconnected from everything.

- nathan.is.an.idiot12312 - Better searching that I. I wasn't able to find a 510 unit at all. Pricey! I'll look at the others as possibilities Thanks!!
- datzenmike, Many thanks! you've been through quite a bit! I must not have mentioned it but when we started on this project, maybe back in August, the frist roadblock was that the turn signal stalk was frozen solid, wouldn't move. We took it off the steering column and had to use quite a bit of heat to get it to the point where is would move enough to flush out that old tan/red grease that had hardened in place and unfreeze it to get it working. Never thought about verifying the electrical connections. Based on what you just described, I'm wondering if we melted some solder. The 30 ohms is just the turn signal switch, completely disconnected from everything. Flasher is not in the circuit.

- Stoffregen Motorsports, Thank you. I am now suspecting that we melted some solder inside the switch area when we unfroze it. The wiper arms were also frozen from the hardened grease. I'll bet there's a solder blob like Mike described. I've read horror stories about getting that switch apart between the balls, springs, contacts, and the phenolic card it's all mounted to. It's definitely a candidate for a 3D printed part.

The issue that I had was that when the key was in the "on" position, the voltage at the coil had dropped down to like 8V (with a ~13V battery) the starter is directly attached to the battery cable so the engine turned over fine but with the extra draw in the battery there's basically zero spark. While I have tried starting the engine yet, I'm confident that we're past that issue - as long as there are not other electrical issues lurking there.

[BZT8FS]

It's been awhile. Some progress, we’re making good headway. Looks like I can now drag & drop some files, I hope you can see them.
The primary issue was that the turn signal switch had the soft short to ground that we’d been trying to find. I must have caused that when I heated it up to unfreeze it, when we started on this adventure it was frozen solid and would not rotate to either left or right to activate the turn signal. When you all pointed me back to this I found different resistance across the left turn versus the right turn as well as about a ~30 ohm short to ground, i.e. our "soft short"!

We never did determine exactly what was causing the issue; we blew the switch out with high pressure (a bunch of gunk flew out) and then sprayed it liberally with contact cleaner multiple times. The resistances are both very nearly equal now to within my ability to measure these small resistances. The flasher flashes properly for both left & right, all bulbs flashing correctly. One of you commented that the entire load goes through these turn signal switch contacts - and indeed it does! I can see why these wear out; LEDs will definitely extend the life of this switch. It's odd that they didn't use a relay, they have relays for virtually everything else.
Now I have adequate voltage at the coil during starting to run the engine.

 

However, I've found another possible anomaly (yes, this really is a nit, but annoying):
If I operate the starter with a remote switch between the battery positive on the starter solenoid and the solenoid activation tab where the BY wire goes, the voltage drop at the coil is roughly 2 volts, I see 10.4V at the coil with 12.4V at the battery.
If I use the ignition switch with the BY wire hooked to the solenoid, I see 9.8v at the coil with a 12.4V at the battery. No other changes.
Tracing this through the ignition circuit, we've found that the ignition switch is the culprit for this extra 0.6V drop (I believe it was banzai510(hainz) who predicted that the ignition switch could be an issue.
We verified that it's the switch by pulling the connector and connecting the #1 (WR) connection to the #2, #3, & #5 with 12 AWG wire (yeah it sparks when connecting #3, but we only do it briefly, long enough to measure the voltage with the engine turning over). When doing so the voltage at the coil is the same as when using the remote switch, 10.4V so it appears that the ignition switch isn't up to the job any longer.
I ordered a replacement (Beck Arnley #201-1174) but it didn't work electrically at all in "start position". Measuring it electrically and looking at the schematics online, I see one difference; on some the #2 contact is connected to the #3 & #5 (as well as #1) in “start” but on others, there's no connection between #2 & #3 in “start” position (that's how the Beck Arnely is constructed). It's not clear how the starter solenoid would activate without a connection from #1 (WR) to #3 (BY) which goes to the solenoid, perhaps earlier cars had different wiring.
Is anyone aware of this difference; is there a part number available for the version like mine which does connect #1 to #2, #3, & #5 in "start" position? These switches are not user friendly to take apart and service.
I've attempted to load an image with the differences from the schematics here: https://ibb.co/xS1whtx

I also attached the image below, hopefully you'll be able to see one or the other.

[datzenmike]

Nissan part numbers are 10 digit so a searched 8812-N1600 but added a 1 in front, then a 2 and got a hit for 610 up till July '73 which is really early production 610s which jumped right on the line after the last 510. Possibly this was on the very very late 510s. It's also used on the '80-'83 S110 200sx. 

 

Oh yeah, what is it? 28810-N1600 is a circuit breaker for the wiper motor.

 

Do you have the build date of your 510?

[BZT8FS]

Yes - build date is 12/72.

 

That first digit really looks like an "8" but it's really faint, so good guess on "2"!

Interesting that they put a CB there, it's also fused.

 

Any ideas on the ignition switch p/n?

Thank you!

[datzenmike]

Well there is the key cylinder and all it does is turn if the right key is used. Bolted onto the back of it is the switch with the wires and contacts. As long as the key works only the switch needs to be replaced. This may be different on the 510 I have a later 710..

 

 

The ignition switch is 25150-A4600 but shows it only goes to '70. Then there's the cylinder block for ign. and starter.... 25159-89900 from '69 on. on the 510 it may be all one part. Got a picture?

[BZT8FS]

Hi datzenmike, Apologies, I wasn't clear.

My 510 and all the ones I recall working on (perhaps fuzzy memory) have a connector that can be disconnected, the wires are not soldered on like the one you showed. The switch part itself is held in place with two screws and can be replaced with the main ignition key mechanism in place (see below - I really like the drag & drop now).

Beck Arnley claims their replacement switch is compatible, it's not. It does not connect the BY wire to the WR wire in start position like mine does. It's a very well made switch from Taiwan. There are many claiming compatibility on Google & on eBay, but I've not been able to determine the specific part number I need. That's what I was asking.

Thank you!

[banzai510(hainz)]

Icehouse on here told me that they are 2switches for a 510. THEY LOOK THE SAME . i REALLY NEVER HAD A PROPLEM. But have added a hot start relay on my 521.

 

 

If you have a electric fuel pump that could load down the ignition of you spliced it from there.

My 510 has a aircond fuse. Some peopl hook up fuel pump to that since its keyed 12volts

 

Edited April 1 by banzai510(hainz)

[BZT8FS]

Thanks banzai510(hainz), I believe that I've verified there are two versions of the ignition switch between the existing one in my car and the BeckArnley replacement I have (visually they look identical , electrically they're not). I've not bee able to determine what the correct p/n for mine is. I'll PM icehouse, thanks for the tip.

Good point, I'll have to track down where I connected the fuel pump, mine also has the aircond fuse. I have the pump underneath in the rear just in front of the cross member and the wire disappears inside somewhere. That could be an extra load causing some of this.

[yenpit]

So the basic Datsun electrical ignition switches on the steering column are the same throughout the 1970's.  Most had terminals on the switch, like BZT8FS is showing, thus a plug on the dash harness.  Some had soldered wires with a plug on the end of the short harness, I think like the B210......??  I am aware of two different MOUNTING styles, which do not interchange............one had a single mounting screw (early?), the other had two mounting screws (late?).

 

You can purchase the 240Z repop ignition LOCK assembly online, comes with the electrical switch, bolts right in to the 70-73 510, plugs right in.  Biggest differences are that the repops are a single sided key & because the 240Z lock assembly is on the right side of the column, the round ID plate OFF-ACC-ON-START is backwards for the 510.  Simply pry the ID plate off & rotate 180deg, mount on left side of the column, done!!

[BZT8FS]

Hi yenpit, Thanks for the reply. The issue isn't with the mechanical portion of the ignition switch. It's the actual removable electrical switch at the back with the 5 pin connections.
Mine is flaky in the "On" position. So I ordered an aftermarket one that others had good luck with. It didn't work so I ordered the OEM Factory version 48750-E7705. It operates the same as the aftermarket one.
The issue is that in the spring loaded "Start" position, there's no connection to the BY wire going to the starter solenoid. The existing switch does connect BY to WR & the others shown in the schematic in "Start".
Neither of the two replacements I have ever connect anything to contact #3, the BY solenoid wire. So something is different in my '73 wire harness than in the earlier cars. I'm not finding what it is and so far have been unable to identify a replacement switch.
Thanks,
Paul

[BZT8FS]

Corrected an error in labeling the terminal numbers on the back of the switch, had the correct wires in the proper locations.

Also discovered that in "Lock" position #4 (LB) wire connects to #2 (BW) wire. I have no idea why at this pointt.

[yenpit]

On 1/4/2024 at 12:19 PM, banzai510(hainz) said:

the BW wire should be the ignition fuse.pull that short should be goneI put a meter on the BW wire at the ballast resistor(remove the wire from ballast) and see if 12volt with key ON, then pull the fuse an see what you get.

 

FYI being a 1973 510, the 1970-1972 wiring schematic will not be 100% correct.  I am not aware of ANY 1973 diagram.  Even Paolo never made it.  However, I think the biggest difference will be the added "switch & HVAC illumination" circuit.  I repaired a 1973 wiring harness, using the 1970-1972 as a guide, worked just fine. 

[BZT8FS]

Thanks yenpit, we've pretty much zeroed in on and mitigated most issues now. The schematic you included is the primary one we've been working with as well as two or three others with more specific detail. I do have the factory service manual specific for the 1973 model year only and it does have some additional wiring detail but is deficient in specifics, particularly with the wiring under the dash that comes in through the firewall so it's been a lot of trial & error.

The primary issue was that the turn signal switch was frozen solid, we removed it and in the process of freeing it up heated it quite hot with a heat shrink gun, this inadvertently melted some solder inside the turn signal switch and I never thought to verify electrical connections before reinstalling it. Getting that corrected fixed the major issue, there's still one additional situation that we're hot on the trail of. I appreciate the input! We still have more hills to climb, mostly around the hydraulics once we finalize the electrical stuff.