My Temp Gauge I Making Me Hot Under The Collar

[floorit426]

I have a non-rally gauge cluster. The other day, 5 seconds after cold start up, I noticed the gauge was pegged on H. I read up and figured (incorrectly) that it was the sending unit. I just replaced that and it still has the same issue. You turn the key to on, wait about five seconds, then the needle sweeps to the other side. The wiring appears to be sound. Does this sound familiar, to anyone? BTW, I had the gauges refurbished by Redline, a few years back.

[dodj]

You have a short in the wiring.

[CudaMoparRay]

You have a short in the wiring.

that would be my guess also.

[Topcat]

Get a Infra red temp gun and verify outside engine surface temps.
I might even have one.

[Mopar5]

Check the resistance of the sender while it's cold would be a starting point before going after wiring

[Mopar5]

I didn't see that you replaced the sending unit before posting even so I would still check the new one, it's happened more than once you get new  dud part.can you disconnect sending unit side and run a good jumper to the guage to bypass the harness and then see what you get? If reading is normal it is the harness wire or the dash gaugep is internally shorted. I would check the guages regulator voltage also

[floorit426]

I did check the resistance, of the old unit, and could not get a reading. That's why I figured it was the problem. Now, the new unit registered 195 ohms, cold, which is three times the resistance it should be, as I understand it. It is also my understanding that, as long as the gauge moves, when power is applied, it is all right.

With that said, I have to admit that everything I "know", I learned in the last day or two.

[dodj]

Your sender should read about 80 or so ohms cold, 10 ohms or so hot.
If your current sender is reading 195, you got the wrong one. BUT, it would definitely not be the cause of the gauge going full sweep.
Turn your key to run, without starting. See what the gauge does.

[floorit426]

With the key on, the gauge still sweeps full to the right. I was doing some more reading about this, last night. I learned that the temp gauge is related to the fuel gauge. I just replaced my tank (not my sending unit), and now it only reads 3/4, when full. I didn't think too much of it, but could it be that the tank isn't fully grounded? I know that electrical does strange things, when not properly grounded. I did install a ground strap.

[Mopar5]

You could try removing the sender side of the wire from the guage and check it for continuity to ground if you have very low or 0ohms then the sending wire could be grounded

[dodj]

You definitely have a grounded wire issue with your temp gauge.

Your fuel level sensor is a different issue

[floorit426]

Thanks. I can live with the fuel issue, but not the temp. I guess the best place to start, would be the bulkhead connector, and work my way under the dash. Everything forward of that, looks okay. Visual is about the only way to find it, right?

[dodj]

Mopar5 suggested earlier to unplug the temp sensor, then turn the key on and see what happens. Did you do that yet?
Visual is a very difficult way to solve electrical issues, do you have a meter?

[floorit426]

When I disconnect the wire, from the sender, the gauge does not move, at all. Mopar5 also suggested that I remove the wire, at the gauge and check for continuity. I will probably dig a little deeper, today, and do that. I think that I will need to remove the cluster, to do so.

[dodj]

Then your new sender has to be the issue. I earlier said it would not be the issue if it was 195ohms cold, but it is obviously not 195ohms. At 195 your gauge would not move. It must be 10ohms or less. Maybe your meter is a little wonky?