gauge voltage limiters

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22dog22

22dog22

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I read about the dash voltage limiters is either in the fuel gauge on the rally dash, or on a none rally dash it should be a push in type, I have a 69 cuda without a rally dash and I do not see any type of push in voltage limiter , since my gas, temp. oil pressure gauges do not work I am not sure where to look ,all sensors are, new wiring is correct any thoughts ?
 
So far as I know if you have an oil pressure gauge (not a light) it is built INSIDE the fuel gauge.
 
I also have never seen a 69 Barracuda without a Rally dash. Here is why the fuel, oil and temp gauges are not working. I would bet the farm the IVR (Instrument Voltage Regulator) in your car is built into the gas gauge. The oil pressure and temp gauges need a power feed from the IVR in the Fuel gauge. Here is how it all works. The fuel gauge has 3 wires on the back, and the oil and temp gauges only have two wires. One of the three wires on the back of the gas gauge is 12 volts power in. That current goes to the IVR inside the gas gauge. The IVR changes the 12 volt current to about 5 volts by opening and closing some points fairly rapidly. The result is a pulsing current of about 5 volts. That 5 volts from the IVR powers the Gas Gauge and goes out to the oil and temp gauges through the second wire on the back of the gas gauge (look at a wiring diagram). The third wire on the back of the gas gauge goes to the sending unit in the fuel tank. When the fuel tank is full, the float is up, and the resistor in the sending unit allows full current (about 5 volts) to flow through to the ground (that is why the tank has to be grounded). When that current is flowing, it flows from the IVR, through the bi-metal strip in the gas gauge attached to the needle and through the sending unit to the ground. The bi-metal strip heats up a little and the needle moves up to full. As the fuel level goes down, the resistor in the sending unit allows less current to flow through the gas gauge. Less current flow means less needle deflection. When the tank is empty, there is no current flow, so the needle will not move off of empty. The oil and fuel gauges work the same way. One of the wires on the back of each gauge is a power in from the IVR, and the other is power out to the appropriate sending unit. When oil pressure or temperature is high, the sending units allow current to flow through the gauge, through the sending unit and into a ground. When oil pressure or temp is low, little or no current flows through the sending unit, so there is little or no movement in the gauge needles. You either need to have the gas gauge repaired, buy a new gas gauge, or re-wire to add a separate IVR. Also, I bet that your Alternator gauge works since it is on a separate circuit. If you have any further questions, feel free to send me a PM.
 
harrisonm said:
If you have any further questions, feel free to send me a PM.
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I'm sure you mean well but in my opinion this is not a good practice, generally. One benefit of this (and other) boards is to "help others" with the free spread of open information. If you guys run off with PMs, this does not happen.
 
Thanks, I had not thought of that. My intent was that if I posted a lengthy reply to help with the diagnosis and repair, others may not want to see that. Thanks a lot for the hint.
 
A gauge with limiter inside will have 3 mounting/contact posts. You'll find only 1 wire attached ( from the noise capacitor ).
 
thanks for the information, I will need to pull out the instrument panel assy, and check the gas gauge unit and then install a newer type of ivr limiter.
 
I installed the integrated circuit on my 64 Valiant. My gauges are quick responsive. It took maybe an hour to take out instrument panel and wire the IC into the board.
 
the difference between a rally gauge and a 64 valiant is night and day , you are going to need to perform surgery on your gas gauge if you are going to install a new regulator , it isn't hard to do but it is very hard to do without destroying the wafer backing that the 3 terminals and the rest of the bits are mounted to . The old regulator bits must be removed by cutting the internal bimetallic bit out . Ben aka DemonIVR has posted how to do this in the past but unfortunately he no longer sells his product or reworks the gauges so you will have to search the internet for the outfit he wholesales to , they have the info posted on how to install the Demon IVR .
 
jimjimjimmy said:
You can disable the old vr without destroying it.
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yes but if you leave the bits in there you are asking for trouble down the road , best do it completely the first time . I agree it can be done and I have done it but he needs to know it's a delicate procedure .
 
All i did was put a piece of industrial starter insulation in between the contact points .
 
jimjimjimmy said:
All i did was put a piece of industrial starter insulation in between the contact points .
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Yup. Just need to use your head. A magnifier, maybe some younger hands, this is not rocket science. "Delicate" science, maybe. Certainly not brain surgery, LOL
 
What works for one might not work for another. The odds are against you. The only correct method is remove one and install the other just as if it were the plug in type. Good luck.
 
I bent the contact of my gauge back so it could not make contact with the other side and without touching any other metal. I then put the face back on the fuel gauge and installed a new instrument panel board because mine was peeling at many of the light contacts. So, I am not sure what surgery you are talking about. I did mine though.
 
RedFish said:
What works for one might not work for another. The odds are against you. The only correct method is remove one and install the other just as if it were the plug in type. Good luck.
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So what are you saying ?
 
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