This is a better example of a bimetal strip used as a switch.

1 hour ago, SteveJ said:

The diagram you posted from the FSM shows a points style voltage regulator aka the bimetal strip. The strip opens the points in a manner similar to the voltage regulator in the charging circuit. Where is the error?

The voltage regulator is on the right side of the fuel gauge.

And it's on the left side of the oil pressure gauge where it is also wired to the temp gauge.

By the way, it looks like the Triumph guys have been replacing the bimetal strip regulator with a solid state regulator.

This link shows the internals.

https://forum.triumphdolomite.co.uk/viewtopic.php?f=5&t=4550

Crap. I've been banned on that site. And it only took one peek...

Hook that gauge up to a 12 volt and make a video. I'd like to see that voltage regulator in action but I don't have a loose gauge...

Hmmm... What about cleaning the contacts on the voltage regulator in there...

Edited January 6Jan 6 by cgsheen1

The oil pressure and temp gauges share a regulator (one reg inside that instrument case) and the fuel gauge has it's own. The ammeter and/or volt gauges do not use a regulator.

Details about how the regulator(s) works:

https://www.classiczcars.com/forums/topic/67803-how-the-gauges-work/

So, Nissan gave an incomplete description of the gauge. Over many years.

Could be worse. They quit describing entirely when they went to the ZX instrument panels.

@Zed is that diagram from the FSM? I'm guessing for the 280 though. I have the 260 FSM and its so full of typos, errors, mislabeled wires etc I don't really trust much, but it is still very useful. A diagram like you posted would be great but doesn't seem to exist...these are the closest two I can find in my book, but no chart showing how multiple devices might share a wire like that

Gonna poke around the 12V and ground stuff if I get a minute today. I'm not convinced the gauge itself isn't just toast but then also none of the gauges work right, so one thing at a time.

On 1/5/2026 at 6:21 PM, SteveJ said:

The diagram you posted from the FSM shows a points style voltage regulator aka the bimetal strip. The strip opens the points in a manner similar to the voltage regulator in the charging circuit. Where is the error?

The voltage regulator is on the right side of the fuel gauge.

@Steve what part is the voltage regulator in here? 12V comes in on the left side of the picture, straight into the white bimetal strip, through the loops, and ends at that little tap in the upper right section, which then goes to ground in the black wire on the right...I think? Is the VR up in that little metal tab at top right where the white wire is soldered on?

36 minutes ago, wheezy said:

@Steve what part is the voltage regulator in here? 12V comes in on the left side of the picture, straight into the white bimetal strip, through the loops, and ends at that little tap in the upper right section, which then goes to ground in the black wire on the right...I think? Is the VR up in that little metal tab at top right where the white wire is soldered on?

I can't explain it any better than what @Captain Obvious did in the thread he linked. Basically that assembly is the voltage regulator.

On 1/5/2026 at 1:23 PM, Zed Head said:

Interesting topic. I've wondered about the "regulator" in the past. I dug around in the FSM, and also read that Ratsun link and think that there might be a problem using that solution with this specific problem. The FSM only shows a regulator being used for the temperature and oil pressure gauge. Not for the fuel and ammeter.

Pulled a few things out to illustrate. Still worth exploring, just not for this problem.

From Ratsun. He's talking about temp/fuel, but that's two different gauges in the Z's.

"You're temp/fuel gauges don't work and you've already checked the output from your fuel/temp sensors to make sure they are not the culprit."

From the 1974 FSM. Looks like three triangles represents the regulator.

The fuel gauge has a heat coil. Seems like that could fail and cause problems. No heat, no needle movement.

39 minutes ago, wheezy said:

@Zed is that diagram from the FSM? I'm guessing for the 280 though.

I posted the two drawings from the 1974 260Z first, quoted above. From Body Electrical. For some reason they showed the regulator in the water and oil gauges, but not in the fuel level gauge.

CO is most likely correct that all of the years used it. There's a bunch on the internet about Ford and Chrysler and various English manufacturers using them, since the 50's and 60's.

If I had the problem I'd identify the wires that pass through the two bimetal strips and measure resistance.

Probably this one. But, really, they're all the same up to 1976.

https://www.classiczcars.com/files/category/12-260z/

12 minutes ago, Zed Head said:

If I had the problem I'd identify the wires that pass through the two bimetal strips and measure resistance.

There would be three.

Edit - and just to confirm what you're probably thinking - it will be difficult. Because the wire colors after the connector are different than the wire colors in the main harness. You'll need to identify the pins in the connectors on the main harness side in order to identify the relevant pins on the other side. Pen and paper and the connector in front of you.

Edited January 8Jan 8 by Zed Head