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fuel/temp gage volt. regulator

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Hi.  My fuel/temp gauge use to go off and on, now they quit working period.  My mechanic and I tore the instrument cluster out and looked at the scematic in a nissan repair manual to troubleshoot.  In the scemetic it shows a voltage regulator in line for those two gages.  When we took the gages out including the speedometer, we could not find a voltage regulator.  No where on the firewall either.  

Anyone know where I can find the fuel/temp gauge voltage regulator?   Thats about the only thing we thought could stop them from working.  When it was intermitent, it may have been going out.  Now it is out.  Thanks in advance.  Bill

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There may be something in this thread that will help (or confuse) you:

http://community.ratsun.net/topic/72080-fueltemp-problem/

This is mostly dealing with 510 instrument voltage regulator so your later 720 regulator location may be totally different.I suppose Nissan may have even gone to some type of solid state regulator by then.In post #14 of the thread, I have a link to a Dropbox page with pics of a 510 gauge cluster and regulator.

 

If the back of your 720 dash looks like the 510 one, be careful which screws you remove to withdraw the gauge cluster. On a 510, it is the 3 outer screws. The four in the center of the board hold the legs that support the gauges and you don't want to remove those.

 

Len

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Thanks Len, I read all the post and looked at your pics of drop.  Sure doesn't look like my gauge's.  Back to the drawing board.  Thx

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It's buried in the instrument cluster.

The wiring diagrams also show it there, my 1982 720 diesel harness shows the power being supplied to the voltage regulator by a yellow/red wire in the smaller gang plug, it's likely behind the speedo gauge.

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60BeeOM.jpg

 

Here it is. The white wire heats up the bi-metallic strip with the  contacts on it, it bends and opens them. Cools and make contact again and repeats. Voltage is held around 8 volts for the gauges. This way they read the same if engine is off and not charging or over 14 when running.

 

Get some fine emery cloth and fold it. Lift open the contacts and close them on the emery cloth. Pull emery cloth through them cleaning any corrosion and polishing them.

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Wow, sure wasn't looking for that kind of regulator.  No wonder we missed it.  Thanks Mike, will give it a try.  So to replace it, you would have to replace the whole gauge?  Racerx, I don't know what a JY is?

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Junk Yard... a wrecking yard... scrapper.... car graveyard.

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60BeeOM.jpg

 

Here it is. The white wire heats up the bi-metallic strip with the  contacts on it, it bends and opens them. Cools and make contact again and repeats. Voltage is held around 8 volts for the gauges. This way they read the same if engine is off and not charging or over 14 when running.

 

Get some fine emery cloth and fold it. Lift open the contacts and close them on the emery cloth. Pull emery cloth through them cleaning any corrosion and polishing them.

Now if I could only figure out how to get one of these regulators to fit 410/411, 520/521 instrument clusters!!! LOL

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Now if I could only figure out how to get one of these regulators to fit 410/411, 520/521 instrument clusters!!! LOL

 

There was a guy several years ago selling regulators for 520/521 gauges made out of transistors, diodes, or some other electrical part that had no moving parts, but there are so few that need that sort of thing and he got no responses, I cannot find the ad, I really don't remember what section it was in anymore.

 

I am thinking it was this in the link below, but not the ad I was talking about.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0ahUKEwjirpeMjsLWAhVU7GMKHc7SAPQQFghmMAg&url=http%3A%2F%2Fcommunity.ratsun.net%2Ftopic%2F54598-bad-gauge-cluster-voltage-regulator-easy-2-fix%2Fpage-2&usg=AFQjCNEte4giLcRfKMvaTxTa4duGCG_zNA

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I have a couple of those some where here.  Thank you Wayno for reminding me.

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Hopefully fixed.  Spent about 4 hours on it this a.m.  Emory clothed it once, cleaned all the plug's, etc. and put back together.  Gauge's worked intermittently, up and down.  So we took it back out again and re-sanded it.  Put back together and nothing, except the idiot lights were working wrong.  Left turn signal didn't light, battery light didn't light until it was running.  Another hour or so checking voltage, etc. until I suggested to my mechanic that maybe we had the two white plugs swapped, he swapped them and all the idiot lights returned to normal, turn signals worked correct, etc, but the gauge's didn't work at all.  I said forget it, I'll put a live gauge for the temp.  We closed it all up and when I started the truck, the gauges worked.  Don't work with key on, only when running??????    Anyhow, they are working for now.  I only need them when its running anyway.  Thanks Mike for the suggestion and picture.  You guys are great.

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Anyone know where to locate the Regulator for the Temp/Fuel Gauge on a 75 620? My cluster is out and in the open, but not seeing anything like this on the inside, nor immediately on the outside.

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It's built right into the gauge. You'll have to split it apart further to get to it.

 

Qn51VX4.jpg

 

Just fold a thin strip of very fine emery cloth, carefully open the points and close them on the paper and pull through to clean them. The one regulator works both gauges I believe. The regulator produces an 8v source for the gauges that is not affected but the varying voltage from the alternator/battery when off, idling or at full charge.  

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try wiggle the wire or resolder the connection.

What I seen its just a wire wind into like  coil. very basic.

just be reinstalling the inst panel might fix it.

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On 3/12/2019 at 5:58 AM, datzenmike said:

It's built right into the gauge. You'll have to split it apart further to get to it.

 

 

Ah! Thanks for pointing that out.

Hopefully this other cluster I grabbed and LED'd will work until I can fix the other for a backup.

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On 3/12/2019 at 7:09 AM, banzai510(hainz) said:

try wiggle the wire or resolder the connection.

What I seen its just a wire wind into like  coil. very basic.

just be reinstalling the inst panel might fix it.

I'll check that out too. Thanks!

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9 hours ago, Rat baby said:

I have an extra oil pressure and battery gauge if you need em. 


I actually had an entire cluster from a 79, I just swapped them out.

But thank you!

Edited by cobra269

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UPDATE:

My 75 appears to have the Regulator external to the gauges, and 4 separate wires, 2 to the regulator, then one from the regulator to the cluster ground. The other 2 wires I am not sure yet, haven't dug that deep into the old cluster.

After swapping the Cluster from a 79 into the 75, direct drop in via the molex, minus the regulator wires and two other unknown wires, all is working perfect again.

Now, it's time to rebuild the old cluster and make it nice once again...

I'll get a picture up soon of the rear of my old cluster and the regulator.... Then try to figure out where those other two wires go inside the old cluster.

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Actually, after getting a chance to get it on the freeway, the Speedometer from the 79 was reading way low, compared to the stock 75 Speedo. 35 mph on speedo, 55 on GPS...

Removed the Cluster, two screws to remove one speedo and put the old one back in, works 100% perfect now! And I'm 100%sure of it now...

Since I was pressed for time, couldn't get a picture of the 2 wires, but they run to a Lever type Switch that is mounted inside the Speedometer, activated by the existing gears. The 79 Speedo did not have such a thing! Any idea what the hell that switch could be for? The switch appears to activate ground since one wire actually attaches to the physical body of the speedo.

Ahh well, be back as soon as I can figure out how to attach pics again.

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