Mopar Gas/Oil/Temp Sensor Simulator

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Mike69cuda

Mike69cuda

Mopar Moron
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Seems like I have had a lot of trouble resolving issues with gauges and sensors on my 69 cuda. Made a simulator for the sensors. The oil, gas, and temp senders have the same ranges (learned that here), so one simulator will work for all. I used some 5 and 10 watt resistors and three switches to make it. I used standard resistor values to get pretty close.
Full is 10 ohms nominal, I used a 10 ohm.
Half is 23 ohms nominal, I used a 22 ohm.
Empty is 74 ohms nominal, I used a 50 and a 22 ohm in series.

I tried it on my non working temp gauge ( which has a new sender) and discovered that the gauge works right on all three ranges. Bad sender looks like.

I made it small enough that it will fit in a USPS small flat rate box, if anyone want to borrow it. Since I bought the parts on Amazon, I got enough parts to make a few more, so I might do that if I get bored.

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I have an old, (working), fuel tank sending unit, which uses a similar ohms range. I am going to try it tomorrow as a test fixture to validate the gauges. I am having trouble getting a rally dash oil and temp gauges to work on a '70 340 Duster we are restoring. Any thoughts? Like your idea, BTW.
 
Handy I built one out of as we say in amateur radio, "homebrew" from the "junk box."
 
BLKNBLU340DSTR said:
I have an old, (working), fuel tank sending unit, which uses a similar ohms range. I am going to try it tomorrow as a test fixture to validate the gauges. I am having trouble getting a rally dash oil and temp gauges to work on a '70 340 Duster we are restoring. Any thoughts? Like your idea, BTW.
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You didn't say if fuel gauge works or not. all 3 thermal gauges operate on a single gauge voltage limiter. It is inside your rally fuel gauge. That's why your fuel gauge has 3 contact posts. Most owners wouldn't know which 2 of these 3 post to connect a tester such as this onto. Your fuel gauge also has a slither of metal on the back of it that grounds it to the inst' housing. Any inst' housing most have a chassis ground path back to battery negative to work. Hope this helps
 
I’ll send you the calibration box if you want to borrow it. Fits in a small flat rate box.
 
Hey Mike, very generous of you, I am almost there, but thanks anyway. And Redfish, thanks for your input. Yes, the fuel gauge works great, and ammeter also. I had already installed the IVR3 solid state unit in place of the contacts/bi-metal strip in the fuel gauge, which was disabled by bending points apart. With engine running, I quickly grounded out the grey wire which is used at the canister style sender, (new), and saw NO movement at the dash gauge, then held it to ground....nothing. BTW, we installed new wiring front to rear of the vehicle and lightly sanded all contact points on circuit board and other points of contact, in addition I added another ground to the instrument cluster and validated its continuity. Previous owner had completely hacked most of the cars wiring to the point where it would start 'ONLY'. Nothing else worked. We are at over 140 gremlins removed/fixed from this 50 yr old car. I also tested the temp gauge by shorting it's connector to ground briefly, and got movement from THAT gauge. That is likely a wrong sending unit for the rally gauge set-up, I will follow up results here once that sender is changed. So, at this point, I am thinking our oil pressure gauge had been toasted by previous owner likely, so I am going to swap temp senders before I pull the whole dash out again and take a closer look at the OP gauge. I appreciate any input or opinions here......thanks !

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I have got multiple bad temp senders from parts stores. I think they are pretty easy to damage installing as well. I measure them using a meter, glass of water, & a microwave now before I install to check for action.
 
I haven't had to do that yet, but have no problem taking an extra minute to do so....,good call !
 
BLKNBLU340DSTR said:
Hey Mike, very generous of you, I am almost there, but thanks anyway. And Redfish, thanks for your input. Yes, the fuel gauge works great, and ammeter also. I had already installed the IVR3 solid state unit in place of the contacts/bi-metal strip in the fuel gauge, which was disabled by bending points apart. With engine running, I quickly grounded out the grey wire which is used at the canister style sender, (new), and saw NO movement at the dash gauge, then held it to ground....nothing. BTW, we installed new wiring front to rear of the vehicle and lightly sanded all contact points on circuit board and other points of contact, in addition I added another ground to the instrument cluster and validated its continuity. Previous owner had completely hacked most of the cars wiring to the point where it would start 'ONLY'. Nothing else worked. We are at over 140 gremlins removed/fixed from this 50 yr old car. I also tested the temp gauge by shorting it's connector to ground briefly, and got movement from THAT gauge. That is likely a wrong sending unit for the rally gauge set-up, I will follow up results here once that sender is changed. So, at this point, I am thinking our oil pressure gauge had been toasted by previous owner likely, so I am going to swap temp senders before I pull the whole dash out again and take a closer look at the OP gauge. I appreciate any input or opinions here......thanks !
Click to expand...
OK, so we'll assume you are getting 5 volts into the temp and oil gauges, and through the temp gauge but not though the oil gauge. Too bad you didn't check them while the panel was out. Ohms meter should show approx' 20 ohms post to post.
3 volt battery attached generating needle movement to a little more than half range. It's not exact but at least a clue that the gauge is alive.
I've seen very few toasted temp gauges. I've seen several toasted oil press' gauges. One known cause... Bare terminal gets knocked off this sender and shorts to ground. It takes a few minutes for zero ohms to fry a gauge. Distributor wrench in LA servicing. It could happen to anyone.
Used gauges are offered here. Some have been tested/proven alive , some have not.
New terminal with plastic insulator for this oil sender is available online somewhere too. Good luck with it.
 
RedFish said:
OK, so we'll assume you are getting 5 volts into the temp and oil gauges, and through the temp gauge but not though the oil gauge. Too bad you didn't check them while the panel was out. Ohms meter should show approx' 20 ohms post to post.
3 volt battery attached generating needle movement to a little more than half range. It's not exact but at least a clue that the gauge is alive.
I've seen very few toasted temp gauges. I've seen several toasted oil press' gauges. One known cause... Bare terminal gets knocked off this sender and shorts to ground. It takes a few minutes for zero ohms to fry a gauge. Distributor wrench in LA servicing. It could happen to anyone.
Used gauges are offered here. Some have been tested/proven alive , some have not.
New terminal with plastic insulator for this oil sender is available online somewhere too. Good luck with it.
Click to expand...
Yes , I did read that info...somewhere, very likely one of your many helpful posts ! (2) 1 1/2 volt DC batts in series and check for gauge movement, will do when I go back into it. I had also read that with the o.e.m. fuel gauge and grounded out O.P. grey wire can toast the oil pressure gauge, as the original , unmodified factory fuel gauge amp draw is more than the IVR3 supposedly, which is also how I proved that gauge defective. I wondered too why Chrysler did not insulate the end of that wire, like the temp violet wire, now you just said the same thing here ! (It will be insulated now). I keep a daily log on all of my most critical mechanical/electrical tasks, but I checked that log and had apparently neglected to validate the O.P. gauge while disassembled as nothing 'appeared' broken. I know better, yet still make mistakes. Valuable info here...thank you sir !
 
Yep, they put rubber booted terminals on temp gauge and fuel gauge. The hard plastic used at this oil sender terminal didn't hold up well. Engine heat cooked them I guess.
 
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