Fuel and temp guage

[Oilspot]

Pretty sure this is an easy fix. Just no time to diagnose and I need the truck this weekend. 

Hadn't driven the truck for over a week because I was outta town. Started it up to drive to work today and there's no fuel or temp guage. I pulled each fuse, did a visual check and turned them 180 lengthwise. Surprisingly to me this didn't fix it. 

Figure I'll check continuity on each fuse with a meter, clean up the contact points quick after I get off work. 

Any other thoughts if this doesn't get it? Ie. Other connections that could need cleaning, does the regulator on the backside of the speedo ever go bad sittin' dormant? 

 

[thisismatt]

4 minutes ago, Oilspot said:

Pretty sure this is an easy fix. Just no time to diagnose and I need the truck this weekend. 

Hadn't driven the truck for over a week because I was outta town. Started it up to drive to work today and there's no fuel or temp guage. I pulled each fuse, did a visual check and turned them 180 lengthwise. Surprisingly to me this didn't fix it. 

Figure I'll check continuity on each fuse with a meter, clean up the contact points quick after I get off work. 

Any other thoughts if this doesn't get it? Ie. Other connections that could need cleaning, does the regulator on the backside of the speedo ever go bad sittin' dormant? 

 

 

They go bad one way or another...not sure exactly why, but contacts may be dirty

[mainer311]

If you lost the fuel and temp at the same time, it's almost definitely the voltage regulator on the back. The old ones use a bimetallic strip that oscillates to regulate the voltage. The contacts sometimes get dirty, or maybe you have a connection that fell off. 

Edited April 7, 2022 by mainer311

[Oilspot]

14 minutes ago, mainer311 said:

If you lost the fuel and temp at the same time, it's almost definitely the voltage regulator on the back. The old ones use a bimetallic strip that oscillates to regulate the voltage. The contacts sometimes get dirty, or maybe you have a connection that fell off. 

I'll try cleaning everything up and hope to get it working again. But I'm thinking getting a replacement regulator is a good precautionary step!!! What's a good source for them? 

[datzenmike]

Cleaning with a folded piece of fine emery cloth placed between the contacts and then pulled out will fix them.  Otherwise...

 

Someone was making an selling these.

[thisismatt]

Making your own is about all there is. The stock regulator is a "pulsed" 8 volts

[mainer311]

There are DC-DC regulators all over eBay. If you get one with a pot, you’ll be able to tune the output.

[Oilspot]

13 hours ago, mainer311 said:

There are DC-DC regulators all over eBay. If you get one with a pot, you’ll be able to tune the output.

My immediate thought "and this how I burn the truck to "the ground!" 🤣

 

I'll need a little further instruction/ guidence on this!!!

[datzenmike]

 

I think this is the 521 VR. You can remove it and carefully pry the case apart to get at the contacts.

 

Without the regulator the gauges would have to work with battery 12v or even lower if idling with headlights and heater on to 14.5 or so volts when the alternator is charging. The gauges would read high when charging and lower when the headlights are on or idling. By creating it's own 8v power supply the gauges are less affected by normal voltage swings 

[d.p]

I would lose both of mine when I first got my truck and I thought it was a fuse but in the end it was my alternator.  Why who the fuck knows but with a lot of things with these trucks some mysteries are destined to never be solved.  

[Oilspot]

30 minutes ago, d.p said:

I would lose both of mine when I first got my truck and I thought it was a fuse but in the end it was my alternator.  Why who the fuck knows but with a lot of things with these trucks some mysteries are destined to never be solved.  

Well the alt and voltage reg are new so that takes that outta the question. I'll finally have a little time tomorrow to look at it. 

Datzenmike if I don't find a fuse/ connection issue somewhere else I'll prob pull the cluster and pry that VR open and give it some attention. I'm really hoping I don't have to pull the cluster. I don't know if I went stupid or it's my big ass hands, but the last time I put the cluster back in I had to fight like crazy to attach the speedo cable.  Like full fledged acrobatic stances.... Cursing at God, the kids, the neighbors!!! 

 

[banzai510(hainz)]

I can reach it and tap on mine then it works

mine will come and go some times.

just fill up and drive and remeber your miles then it might coem back to life after you hit a bump

[datzenmike]

3 hours ago, banzai510(hainz) said:

 

just fill up and drive and remeber your miles then it might coem back to life after you hit a bump

 

Bet you have a brick for an e brake and a bungee cable for the battery tie down.

[mainer311]

This is all you need. The small blue thing is a potentiometer. You feed it truck voltage, then turn the knob on the pot until you get 8 volts output. It uses a switching regulator for "bucking" the voltage, and even has a nice digital readout.

 

https://www.digikey.com/en/products/detail/dfrobot/DFR0379/7087190?utm_adgroup=Evaluation Boards - DC%2FDC %26 AC%2FDC (Off-Line) SMPS&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Development Boards%2C Kits%2C Programmers&utm_term=&utm_content=Evaluation Boards - DC%2FDC %26 AC%2FDC (Off-Line) SMPS&gclid=CjwKCAjwur-SBhB6EiwA5sKtjrvvECuJslU9GQE2Usz8pxeKG1tUkjq60Z0oRoxkkK-1jUfTyF9GzxoCG9QQAvD_BwE

Edited April 8, 2022 by mainer311

[Oilspot]

3 hours ago, mainer311 said:

This is all you need. The small blue thing is a potentiometer. You feed it truck voltage, then turn the knob on the pot until you get 8 volts output. It uses a switching regulator for "bucking" the voltage, and even has a nice digital readout.

 

https://www.digikey.com/en/products/detail/dfrobot/DFR0379/7087190?utm_adgroup=Evaluation Boards - DC%2FDC %26 AC%2FDC (Off-Line) SMPS&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Development Boards%2C Kits%2C Programmers&utm_term=&utm_content=Evaluation Boards - DC%2FDC %26 AC%2FDC (Off-Line) SMPS&gclid=CjwKCAjwur-SBhB6EiwA5sKtjrvvECuJslU9GQE2Usz8pxeKG1tUkjq60Z0oRoxkkK-1jUfTyF9GzxoCG9QQAvD_BwE

I ordered one

[banzai510(hainz)]

On 4/8/2022 at 12:30 PM, datzenmike said:

Bet you have a brick for an e brake

yes!!!!!!

I have a nice battery tie down

 

 

oilspot just reseat the plug in back and it might work again.

Edited April 9, 2022 by banzai510(hainz)

[dat521gatherer]

Check this rivit.

[dat521gatherer]

 

[dat521gatherer]

Lots of good regulators out there. Ask around. Also make sure your cluster is making a good ground contact through the mounting brackets.

[dat521gatherer]

Taken from my green 521 thread. Another cluster problem just FYI.

 

I also put some leds in the dash lights. While I was in there I repaired a bad ground rivet  that would make my left blinker light stay lit in the first pic. I would reach under there and tap the circuit board and the blinker light would go out for a while then come back on and stay lit when I tried to use the left blinker. I had this same rivet problem with my fuel gauge falling to empty again I would reach under the dash and tap the gauge volt reg and my fuel needle would jump up.

http://i272.photobucket.com/albums/jj172/dat521gatherer/datsun 521 1971 green/SANY8033_zpslfsx1swb.jpg

http://i272.photobucket.com/albums/jj172/dat521gatherer/datsun 521 1971 green/SANY8037_zps81eyh3t1.jpg

http://i272.photobucket.com/albums/jj172/dat521gatherer/datsun 521 1971 green/SANY8042_zpsy2letoko.jpg

http://i272.photobucket.com/albums/jj172/dat521gatherer/datsun 521 1971 green/SANY8045_zpscqv2dcvn.jpg

Edited April 12, 2022 by dat521gatherer