SteveJ

The fluctuation of the test light is right in line with the operation of the oil pressure metering circuit. If you measured voltage to ground where you put the test light, you would see fluctuating voltage. It would be easier for you to read the ohmmeter at the 200 ohm setting, but it appears as though the sender is working. It was disconnected from the wire from the gauge, wasn't it?

Thanks for the verification. At 15.7, the charging system is running high. Is that how it has been running, or have you changed out the alternator or voltage regulator? By the way, did you ever check the sending unit for resistance?

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.

Even if it just drops the air temp in the cabin to the mid 80s, that would be a BIG improvement for me.

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.

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.

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?

That's not a lot of weight if you live in the Southeastern US. You should have seen me after driving to Memphis and back for ZCON 2015. I would not have minded and extra 70 lbs at all for that trip.

Was 15.7 measured with a multimeter or read from the gauge in the car? This is why I like those cigarette lighter voltmeters. They are usually pretty close to a multimeter, and you can see the voltmeter and tachometer at the same time.

I remember seeing the post of the ignition switch wiring diagrams through the years. It's easy enough to verify on my 73. I just have to lift the solenoid wire off and have the turn signals on. If I have turn signals blinking while starting, then it has power while cranking. The 70 FSM indicates it is not powered during start. The wiring diagram in the 71 supplement shows the same, and the 71 Body and Chassis Part 2 PDF matches. The parts manual also indicates there were separate designs originally. I still have a new D8700-E4629 (in Beck Arnley packaging) that according to Courtesy Parts's website "Replaces: 48700-E4600, 48700-E4625, 48700-E4629" I did a continuity test on that switch and here are the results: (Red indicates continuity with the WR wire, and black indicates no continuity.) OFF Acc On Start So the BW is hot on that switch in start. Either D8700-E4629 is not faithful to the original design or the wiring diagram is wrong. Either way, I took the video Private until I can confirm so I don't muddy the waters with it.

Make sure you get the plug wires seated far down enough in the cap. If there is a gap, it will arc between the cap and plug wire, eating away at the plastic in the cap. As for the fuel pump, a couple of years ago I replaced the fuel pump one someone's car with a Delphi pump. I wasn't happy with the results, so I swapped the diaphragm over from the Delphi to the stock fuel pump. The old pump ran great with the new diaphragm.

It doesn't hurt to check your fuel pressure. Also, are you sure your float levels are set properly?

When it dies, does it happen gradually or suddenly?

Now, if there are issues when the key is in ON, that's a different kettle of fish, as long as you understand it doesn't see voltage during the cranking cycle.

Which BW wire are you talking about? The BW at the switch doesn't get power until the key is in the ON position. Maybe this video will help you figure out what you're looking at. (Note: Video removed as I cannot confirm at this time that the switch operates as shown in the wiring diagrams.)

Your MOV files aren't embedding properly. You'd have better luck uploading them to YouTube and linking them that way.

Yes. Here's a link to resistance values posted by someone on Hybridz. https://forums.hybridz.org/topic/114259-oil-pressure-sender-and-gauge-specifications/

The test light isn't a definitive test. However, here's how to test the gauge:

That's what I was thinking when I looked at the 4mm rod I received today.

Brass certainly won't be brittle, and it won't melt easily. I don't know about friction, though.

All you have to do is magically contort your arms to reach behind the evaporator and use your x-ray vision to see the wires & connectors.

Don't forget about cleaning the connections on the fusible links, too. Dang, that's LOW oil pressure.

No, it was just a lack of knowledge. Dumb would have been leaving it there after you have learned about how you needed things to work. And, BTW, my suggestion about de-pinning the BW wire from the engine harness connector probably would have removed that issue, too.

Not really. That is the wire out to the solenoid. You can take the other end off the solenoid and read it again.

In the first photo, you can see the fan is blurred, so the car is running. Unless @240zadmirehad not tried to rev the engine to excite the alternator before that photo, the voltage is low. Since the alternator and battery are connected, you should see the same voltage at both. The only thing that would drop the voltage at the battery is corrosion.