Temp gauge issues

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Jake1974dart

Jake1974dart

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San Dimas California
Hello fellow FABO people I have a 1974 Dodge Dart swinger and I am having a problem with the temp gauge reading way past overheating even when the motor is dead cold I had the gauge cluster out today and checked to make sure is it connected to the cluster correct and clean and it was so I am asking is there anyway to fix this before I have to cough up the 130 bucks to classic industries thanks for your time
 
You have a short in the wire to the sender, more than likely.
If you ground the wire...its reads HOT.
Probably ground on the intake.

Or... the sender is bad.
 
Last edited:
A few questions to troubleshoot:

Are other gauges reading correctly?

Does the gauge stay pegged all the time, or just with the ignition on?

If you unhook the wire on the sender, does the gauge drop to zero?
 
Mike69cuda said:
A few questions to troubleshoot:

Are other gauges reading correctly?

Does the gauge stay pegged all the time, or just with the ignition on?

If you unhook the wire on the sender, does the gauge drop to zero?
Click to expand...
All the other gauges work it’s just that one and it stays pegged even when running. I just went out there and unplugged it from the sender and it went down to 0 this is the factory gauge
 
All gauges except the ammeter are a simple series circuit, functional path is from ignition switch.........to cluster.........through the instrument voltage limiter.............branches off to feed power to the fuel/ temp/ oil gauge if equipped.........through each gauge..........back to the sender.........to ground

So if the fuel works OK the power/ IVR is OK, that leaves the gauge unit, the sender wire, and the sender.
If the gauge drops with sender disconnected, it's the sender

If not, suspect the sender wire. About all you can do is pull the cluster to access the wire which appears at the cluster connector
 
67Dart273 said:
All gauges except the ammeter are a simple series circuit, functional path is from ignition switch.........to cluster.........through the instrument voltage limiter.............branches off to feed power to the fuel/ temp/ oil gauge if equipped.........through each gauge..........back to the sender.........to ground

So if the fuel works OK the power/ IVR is OK, that leaves the gauge unit, the sender wire, and the sender.
If the gauge drops with sender disconnected, it's the sender

If not, suspect the sender wire. About all you can do is pull the cluster to access the wire which appears at the cluster connector
Click to expand...
Ok so then maybe I got a bad sender because the gauge drops when I disconnect from the sender
 
^^Actually you could still have a bad gauge unit or bad IVR. The IVR can be "tested as good" if you can confirm the fuel gauge works OK, as both gauges get power from it.
You can buy resistors use to test the sender, or you can measure the sender resistance to determine about what the gauge SHOULD read. Do a search here. There are hundreds of threads on this

67dart273, gauge tester - Google Search

Post no2

Miller c-3826 tester found?? Any interest?

c-3826-jpg-jpg.jpg
 
Ohm out the sender cold it be 74 ohms, new ones suck had issues with them new.
 
74 model has a white plastic engine harness connector on right side of engine bay. It has temp sender wire, alternator wires, etc.., in it. These connectors do melt down to cause short circuits but... "sender disconnected, gauge needle goes home" does suggest a bad sender. No fault in that harness connector. Look at it anyway.
These senders typically fail to open instead of closed though. Ohms meter on the sender will prove it good or bad. With the radiator cap removed we can see when the thermostat opens. At that time the temp sender should show somewhere around 35 ohms.
Here's the thing... your temp gauge is the old standard 20 ohm gauge. Your fuel gauge is the only other gauge on this circuit and its a later design 13 ohm gauge. You can check that with a ohms meter post to post on the gauges as well. Neither gauge should show continuity from a post to can/chassis ground. If the temp gauge does... its bad.
For this model/design, a faulty instrument voltage regulator will show itself in the temp gauge ( wild needle swings ). The fuel gauge may be a bit erratic, show more gas than you actually have. The 13 ohm fuel gauge isn't as accurate as the earlier 20 ohm gauge but... it runs cooler, lives longer.
Bottom line... proving sender, gauge, wiring between are good, suggests the limiter is the culprit.
 
67Dart273 said:
^^Actually you could still have a bad gauge unit or bad IVR. The IVR can be "tested as good" if you can confirm the fuel gauge works OK, as both gauges get power from it.
You can buy resistors use to test the sender, or you can measure the sender resistance to determine about what the gauge SHOULD read. Do a search here. There are hundreds of threads on this

67dart273, gauge tester - Google Search

Post no2

Miller c-3826 tester found?? Any interest?

View attachment 1715415957
Click to expand...
Thank you for the information. My fuel gauge does work I will test the sender and see if that is still the culprit.
 
RedFish said:
74 model has a white plastic engine harness connector on right side of engine bay. It has temp sender wire, alternator wires, etc.., in it. These connectors do melt down to cause short circuits but... "sender disconnected, gauge needle goes home" does suggest a bad sender. No fault in that harness connector. Look at it anyway.
These senders typically fail to open instead of closed though. Ohms meter on the sender will prove it good or bad. With the radiator cap removed we can see when the thermostat opens. At that time the temp sender should show somewhere around 35 ohms.
Here's the thing... your temp gauge is the old standard 20 ohm gauge. Your fuel gauge is the only other gauge on this circuit and its a later design 13 ohm gauge. You can check that with a ohms meter post to post on the gauges as well. Neither gauge should show continuity from a post to can/chassis ground. If the temp gauge does... its bad.
For this model/design, a faulty instrument voltage regulator will show itself in the temp gauge ( wild needle swings ). The fuel gauge may be a bit erratic, show more gas than you actually have. The 13 ohm fuel gauge isn't as accurate as the earlier 20 ohm gauge but... it runs cooler, lives longer.
Bottom line... proving sender, gauge, wiring between are good, suggests the limiter is the culprit.
Click to expand...
That’s a good point! I will check the connectors between that engine harness worse case I can solder them together
 
I have got multiple bad senders from the auto parts stores on two different cars. Cheap Chinese crap even on the name brands. I solved the problem by buying OEM from the dealers. Costs more but they work.
 
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