Fuel gauge wiring question

[Johnny Dart]

I would get it back to the way Ma Mopar designed it first, before improving it into a failure.

On another note. There is a ground strap from the sending unit to fuel line that is often missing. Make sure it is installed, and grounding correctly. These are often missing, and the reason the gas gauge is no worky.

 

[70SwingerGuy]

You can also just clip and remove the black wire, and clip the metal spring with the contactor point and remove it, then leave the rest. You want the gage pointer to remain functional.

View attachment 1716186727

In the RTE instructions, it says to bend the limiter points out of the way, and their diagram does not show a black wire to cut, am I correct to assume that they are just using an old scrap gauge that doesnt have a wire for illustration purposes? Also, in your picture that shows the bundle of three wires, it does not show the ground attaching to the new ivr, so Im assuming that its just a ring terminal that goes under the mounting screw of the irv then to the ground on the circuit board?
As before, thanks for all the help!

 

[70SwingerGuy]

I would get it back to the way Ma Mopar designed it first, before improving it into a failure.

On another note. There is a ground strap from the sending unit to fuel line that is often missing. Make sure it is installed, and grounding correctly. These are often missing, and the reason the gas gauge is no worky.

View attachment 1716186740

Thanks for this! Ill make sure to check and verify that it is there and in position

 

[moparmat2000]

In the RTE instructions, it says to bend the limiter points out of the way, and their diagram does not show a black wire to cut, am I correct to assume that they are just using an old scrap gauge that doesnt have a wire for illustration purposes? Also, in your picture that shows the bundle of three wires, it does not show the ground attaching to the new ivr, so Im assuming that its just a ring terminal that goes under the mounting screw of the irv then to the ground on the circuit board?
As before, thanks for all the help!

Yes, I just attach the black IVR wire to the circuit board grounding screw. They must have used a scrap gage. That black wire inside the gage is the 12V feeding the points IVR. You can just bend the points on the wire wrapped bi metal spring out of the way, but I clipped the black wire and removed the vibrating point regulator, left the gage side intact.

 

[moparmat2000]

I would get it back to the way Ma Mopar designed it first, before improving it into a failure.

On another note. There is a ground strap from the sending unit to fuel line that is often missing. Make sure it is installed, and grounding correctly. These are often missing, and the reason the gas gauge is no worky.

View attachment 1716186740

Those vibrating point IVRs are 50 years old. They fail open and closed. Upgrade to better solid state. Nice electronics project that's about $10

Just because mopar designed it, doesn't mean it was all designed great. That ammeter setup isnt that great. Better off bypassing that firehazard.

Some stuff is better than the way the factory designed it 50 years ago.

 

[Dana67Dart]

the RTE instructions state to mount it to one of the circuit boards grounding points

The housing of the IVR MUST be grounded. Depending on where you mount it you may just need to install a screw or a short wire to the mounting screw to a ground source

 

[CFD244]

In the RTE instructions, it says to bend the limiter points out of the way, and their diagram does not show a black wire to cut, am I correct to assume that they are just using an old scrap gauge that doesnt have a wire for illustration purposes? Also, in your picture that shows the bundle of three wires, it does not show the ground attaching to the new ivr, so Im assuming that its just a ring terminal that goes under the mounting screw of the irv then to the ground on the circuit board?
As before, thanks for all the help!

Sorry if I am muddying the waters.......@moparmat2000 is using a different IVR than the RTE in my original post (I assume that is the one you purchased). The unit will be grounded (no extra ground lead) once you attach it to the noise suppressor hole in the gauge frame. Then it's just 12v in and 6v out.

 

[70SwingerGuy]

Sorry if I am muddying the waters.......@moparmat2000 is using a different IVR than the RTE in my original post (I assume that is the one you purchased). The unit will be grounded (no extra ground lead) once you attach it to the noise suppressor hole in the gauge frame. Then it's just 12v in and 6v out.

Not at all! Thanks for helping to clear that up for me, as if you cant tell, I like to cover all the bases before starting an important job

 

[moparmat2000]

Yes my IVR is a homemade deal and not a product by RTS. With a little basic electronics knowledge and soldering prowess you too can make your own

Yes the schematic shows 2 grounding points on my IVR schematic one ground point is on the mounting/heatsink tab, the other is one of the pins on the semiconductor chip. Always consult the pin out on the semiconductor chip bag for correct input, output, and ground pin location on the chip.

As a side note the NTE960 is designed to take up to 35V DC input and convert it to 5.5V DC output. Running 13V through it is nowhere near its maximum duty cycle. This chip should last for years and years.

Use a capacitor between 5 and 100uF and a voltage rating of 15V or more.

 

[Johnny Dart]

Those vibrating point IVRs are 50 years old. They fail open and closed. Upgrade to better solid state. Nice electronics project that's about $10

Just because mopar designed it, doesn't mean it was all designed great. That ammeter setup isnt that great. Better off bypassing that firehazard.

Some stuff is better than the way the factory designed it 50 years ago.

I have done the solid state upgrade before, and yes it is better electronics. My point being, sometimes it is better to get the car back to spec/factory and working properly, so you know what you are working with, especially when the OP admits that wiring is not his specialty.

In my time playing with Mopars, I have never had to replace or change from a factory ammeter. Or the MAD conversion. The key to having ammeter issues is to make sure the 2 wires to the back of it are tight. But like I said, I have never had an issue with an ammeter, bulk head connector, etc. Just lucky I guess.

 

[moparmat2000]

I have done the solid state upgrade before, and yes it is better electronics. My point being, sometimes it is better to get the car back to spec/factory and working properly, so you know what you are working with, especially when the OP admits that wiring is not his specialty.

In my time playing with Mopars, I have never had to replace or change from a factory ammeter. Or the MAD conversion. The key to having ammeter issues is to make sure the 2 wires to the back of it are tight. But like I said, I have never had an issue with an ammeter, bulk head connector, etc. Just lucky I guess.

I agree 100% on making sure its all hooked up right and has proper grounds first. Back in the late 1980s I had a 68 charger who's gages had a mind of their own. I changed out the circuit board with the IVR on it and problem went away. I was just an 18 year old kid back then. This forum wasnt around yet, and Algore had not "invented the internet" yet lol. I assumed it was the circuit board even though I couldent find anything wrong with it. I did the MAD bypass inside the car, but bypassed the alternator output directly to the battery on the engine side along with a fusible link, and not through the bulkhead since it was not necessary since I got rid of the ammeter.

 

[moparmat2000]

If you are replacing the OEM rally fuel gauge, you may want to consider doing the solid state IVR upgrade.

The OEM uses an archaic mechanical voltage limiter integrated in the fuel gauge to supply the 5-6 ish volts needed to run the other gauges (Not amp gauge). By defeating the switching effect in the gas gauge, and using a solid state voltage limiter in it's place, you reduce the chance of a closed failure supplying full voltage to your gauges and frying them.

***EDIT*** Disregard the red and black jumpers......They power the ammeter to voltmeter conversion.

View attachment 1716185255

I love your setup with the solid state IVR

 

[moparmat2000]

When I purchased my 70 Swinger, it had an aftermarket fuel gauge under the dash, due to what I soon discovered was a missing needle on the factory fuel gauge. I managed to find another correct fuel gauge to put back in, but I dont know how to rewire it. I havent taken the cluster out yet, so I thought I would ask in advance if anyone knows what I do with the wire coming from the tank. Wiring is not my specialty...haha
Thanks for any help!

The aftermarket fuel gage is likely spliced in to the factory fuel tank sender wire somewhere under the dash, and the wire going up to the cluster is either cut, or was tapped into.

 

[CFD244]

I love your setup with the solid state IVR

Your postings were invaluable to me when I did the dash work.

 

[Dana67Dart]

I love your setup with the solid state IVR

Just my 2 cents...

The RT IVR has cir protections and it has an initial start procedure that works like the OEM electrical mechanical IVR.

I would rather fork over the extra cash and have those features.

 

[S'cuder]

There's another way to disable the voltage limiter in the fuel gauge without cracking it open.

FABO member @RedFish and his brother devised this method several years ago, and have performed it several times for themselves and others. I learned of it after I posted the RTE method, and Redfish subsequently posted his simpler, easier fix.

This covers the limiter disabling. You can find more here on FABO by searching limiter and disable by Redfish in the search box.
It is not necessary to remove a gauge cover and bend something to isolate that mechanical limiter and substitute a solid state regulator. All that you really need to do is 2 steps... Lift the 3 post gauge and cover a slither of metal on its back side with electric tape to isolate it from chassis ground like any 2 post gauge is isolated from chassis ground.
Since the switched 12 volt wire to the limiter in the fuel gauge serves nothing more in the inst' panel (blue with white tracer), back it out of the round harness and route it to whatever solid state regulator mounted anywhere you want. Route the substitute regulators 5 to 6 volt output to anyone of the traces on circuit board that carries that current and you are done.

 

[S'cuder]

I'm trying something to take @RedFish 's method a step further. Instead of tape, I took a piece of plastic cut from a milk jug and made an insulator.

Here you can see the metal grounding tab on the back of the fuel gauge.

This is the area on the cluster housing that the gauge grounds. The white reflective paint appears to have been ground off to make good contact.

Here's the plastic insulator in place.

Thanks, Redfish! I've learned a lot from your posts. I'm sorry to see you've been posting here less frequently of late.

 

[RedFish]

Yes, I just attach the black IVR wire to the circuit board grounding screw. They must have used a scrap gage. That black wire inside the gage is the 12V feeding the points IVR. You can just bend the points on the wire wrapped bi metal spring out of the way, but I clipped the black wire and removed the vibrating point regulator, left the gage side intact.

View attachment 1716186825

The downside... no matter how many places you ground the solid state regulator to the cast metal inst' housing, nothing is chassis grounded until that housing is chassis grounded. You'll need to add a ground jumper to batt' negative before attempting any bench testing. Reason being, If this type regulator isn't grounded properly It has no ground reference. It will pass full system input voltage straight through and out to all gauges. If the battery should be a bit low at initial start up there is really no guessing how many volts the 3 thermal gauges would receive. I always added an actual ground wire from inst' housing to the car chassis to insure a ground. In cases where the customer sent me their entire assembly for service I would strongly suggest my converting their amp gauge to a volts gauge. That volts gauge needs a chassis ground wire added also. My ground wire would link the IVR and volts gauge volts gauge ground and anchor at the lower screw of center pod. Approx' 4 inch length of wire went from there to male and female spade terminals so this added ground the wire could be unplugged like everything else on the panel. Then ground wire would terminate behind the left kick panel, more or less mirroring the factories ground wire behind the right kick panel. End user could place panel just close enough to make all connections and test everything in the car before ever installing any of the mounting screws or raising steering column into place. But hey, I spent 2 years developing and refining rally panel servicing before offering to the public. As far as I know, after 16 years I still don't have 1 dissatisfied customer.

 

[moparmat2000]

Oh I hear you. I have made a grounding strap for the die cast cluster housings on my junk that bolt to the steering column mounting bolts. Otherwise the only grounds the cluster gets are from its mounting screws. Time and age that becomes a problem.

 

[RedFish]

Oh I hear you. I have made a grounding strap for the die cast cluster housings on my junk that bolt to the steering column mounting bolts. Otherwise the only grounds the cluster gets are from its mounting screws. Time and age that becomes a problem.

Yeah a crowd of owners/ DIY type do use steering column mounting for a ground point. I had done the same in the beginning. Later it occurred to me that if at some point in the future I might need to partially pull the inst' panel for light bulb R&R or any other simple service I would need to lower the column. Right away I would loose my added ground. Thus the pre reinstall testing is lost.
I want to go back to another members earlier post for a bit. He more or less quoted what I had posted in similar threads concerning the rally panel. I want to elaborate on the 12 volt side of the 3 thermal gauges. Ma mopar used a blue wire with white tracer. In my 67-model fish. That wire begins at the ignition switch. Two of the same color wire are in one terminal of harness switch connector. The other of the two goes through the firewall to the system voltage regulator and everything else under the hood that requires 12 volts. Neither is fused (other than the fusible link outside the firewall). So yes there are two regulators getting 12 volts from the same color wire. No fault in that but... If the instrument voltage regulator is not going to be inside the fuel gauge, there is no need to put 12 volts in this gauge. Those 2 post gauges (oil and temp) don't get 12 volts fed to the inside of them. That's why I back this blue w/ white out of the round inst' panel connector and routed it directly to the added solid state regulator no matter where I choose to mount the thing. So now one must ask is there a benefit in this extra mod' effort. If you do enough research, you'll surely find loose or broken pins on the circuit boards. With further research you'll find pictures of printed circuit boards Showing the copper trace from this pin to fuel blistered completely away from the board and burned open. Yep, there was a short circuit somewhere and that tiny copper film served as a fusible link. This happened more often on the earlier panels that house only 2 of the thermal gauges (no oil gauge) but it could happen to any. An inline fuse holder is cheap enough. It's simple enough to place these fuse holders behind the column door so that is the first place my blue w/white goes. Then onward to my IVR and volts gauge.
Although I've never had a problem, if all of 4 of my gauges failed at once I would need to remove 4 screws and drop the column door to check a fuse. Inline fuses for my aftermarket stereo are located there too so they are labeled which is what. I've went so far as to modify factory wiring diagrams, document all the changes and place this info in the glovebox for the next owner.
So my train of thought is/was to recognize all the problems others have had and hopefully avoid them in my own car. I don't expect everyone else to ride the same train. Do as you see adequate (please yourself). Afterall, fuses don't blow for no reason. If I do find a blown fuse I have to dig in and discover why.

 

[RedFish]

I always adjust from the neutral position

Yes my IVR is a homemade deal and not a product by RTS. With a little basic electronics knowledge and soldering prowess you too can make your own

Yes the schematic shows 2 grounding points on my IVR schematic one ground point is on the mounting/heatsink tab, the other is one of the pins on the semiconductor chip. Always consult the pin out on the semiconductor chip bag for correct input, output, and ground pin location on the chip.

As a side note the NTE960 is designed to take up to 35V DC input and convert it to 5.5V DC output. Running 13V through it is nowhere near its maximum duty cycle. This chip should last for years and years.

Use a capacitor between 5 and 100uF and a voltage rating of 15V or more.

View attachment 1716186918

I'm quite pleased to see "heatsink", "finned heatsink", and mention of compound noted on your drawing. Sure some portion of the heat would wick out into the mounting tang of the unit but we must understand that the heat is generated inside the chip. Thus the heat is concentrated in the part of that tang that is behind where we see NTE 960 shown on the chip in your drawing.
As the chip warms the output voltage will slowly rise.
I don't recognize the application shown in this link, Voltage regulator for gauge cluster – GoWesty but I can't imagine that chip living a long life without a lot of air circulation beneath the dash. I haven't found that in any vehicle. Brother and I put a lot of time in testing the different heatsink designs and different brands of regulator available at digikey. While I forget the brand name I/we settled on we did find what worked best/consistently. It would top out at 5.42 on the workbench with no load on the output.
I would order materials in quantities of 30 to 40. There was one time that Digikey took the liberty of substituting another brand regulator. Those things were all over the scale. Some would start at only 4.6 and climb to nearly 6 in same test conditions. Of course, I called digikey and pitched a biotch. They made it right after admitting what I had ordered was out of stock at the time.
So I started all this at about 48.5 yrs old. Today I'm closing in on 67. So much has changed during those What? 19 years. I did some reading around via a Google search yesterday and I must admit my brother understands much more of the data than I do. Today we would need to start over. I'll ad that a lot of what I found in search results was about 3.3 output regulators which I assume is related to LED applications.
In closing I have to suggest everyone just pony up for the RTE IVR for their gauges. Assume RTE is using quality components in their units and will stand behind whatever warranty they provide.
My IVR has never failed and I wont predict it will someday. If it does happen while I own the car, I will step up to the RTE unit. Enough said

 

[RedFish]

@S'cuder You can use a 10-32 die with a drop of lube to clean those rusty contact studs. It's a tedious chore since a handle wont go there. Fingers only. My 10-32 die from Harbor Freight just barely fits between the studs. The factories stamped tin nuts contact only 1 thread of the stud. Since they are hollow, they don't plant the standard ring terminal very will either. That's why I would go to Home Depot and get the little orange bags, internal toothed washers and true 10-32 hex nuts to attach my wires to the gauges etc... Less than a dollar per package. Just be careful in tightening the nuts. No power drivers. That fiber board is easily broken. The studs are just swedged into a square hole. Good luck

 

[Dana67Dart]

Just be careful in tightening the nuts. No power drivers. That fiber board is easily broken. The studs are just swedged into a square hole

You said a mouthful there. I broke a perfect temp gauge just trying to remove the speed nuts.

Now I use jam nuts to hold the stud before trying to remove the speed nuts.

 

[RedFish]

You said a mouthful there. I broke a perfect temp gauge just trying to remove the speed nuts.

Now I use jam nuts to hold the stud before trying to remove the speed nuts.

My brother (actually an electrical engineer in training) says the weaker nut is the mechanical engineer's manner of suggesting/showing a weak foundation, being the way such a large stud is attached. The studs might have been much smaller diameter or even a totally different manner of attachment conducting the current. Consider the spade terminals used at the outboard mechanical limiter found on standard panels. How GM instruments are attached is very similar to that. Just plugged in male to female conductors. So why did Chrysler have 3/16 diameter studs of several times more length than needed? One would have to pose that question to Stuart-Warner since they made these instruments for Chrysler. I'll assume only because that is what their production line was already set up for. Afterall, they made instruments for tractors and all sorts of applications that experienced much more vibration long before that got this Chrysler contract. Anyway...
I too came across a few gauges with very rusted studs and I did break a backboard to learn cutting that weak nut away with a Dremel tool was my method to conquer.
In the final year of my gauge servicing I did end up reproducing half dozen backboards from F4 fiberglass. Approx' same thickness as OEM fiberboard. Reason being, In a few cases the owners OEM boards were so water damaged, warped, and brittle that I didn't have another option. At least 1 arrived here already broken.
I can't say for certain that I still have 1 of those homemade boards here but I'm sure I still have my mechanical drawing of it. The swedge tool is a "one off" that was made for me by a local machine shop that I had once worked for. Yes I recycled/reused the OEM studs.
I image that someday when I'm gone, my junior or someone will pick it up and wonder... WTF is/was this used for? LOL

 

[Dana67Dart]

I have one gauge that is in the 67 to 70 something dart type gauge range that had a plastic board where the fiber board would be. Seemed OEM