Hello,

I am having a problem with my water temp gauge. it is constantly reading cold no matter the engine temp. I tested the gauge by grounding the wire to the temp sending unit on the block to the batter and the gauge pinged to the max. I have tried replacing the temp sending unit twice. i put a resistor in between the sending wire and the battery, and the range to where it showed up past resting(somewhere between cold and hot) was between 10-40 ohms, where the cold line was at like 40 ohms and the hot line was around 10 ohms. I tested the new temp sending unit and at room temp, the ohms were around 500 and at around 200-212 degrees, the ohms were around 50-60. What could be the issue?

 

Did you put any thread sealer on the new sensor? It grounds via the intake manifold, so, additional sealer is a no-no.

 

no, i made sure to not put any thread sealer on it

 

May have just been a bad sensor then. Wouldn't be the first time a bad part came right out of the box.

 

thats what i thought as well, but i have tried 2 new sensors from 2 different manufacturers, but both seem to read the same ohm readings

 

That's odd. One wire sensor, right??

What are you working on, and what is the manufacturer/part number of the sensor?

 

That's correct, one wire. The vehicle is a 1989 dodge d100 with the 3.9L V6. I unfortunately do not know the original manufacturer part number. The one I bought was "Standard Motor Products TS205"

 

Looking that up, I don't think that is correct...... the site I found it on can't make up its mind if that is a level sensor, or a temp switch. (not sensor) Looking the sensor up on rock auto, they have a selection of two wire sensors, which I expect is for the PCM, the one wire sensors just have a stud...... What does the connector on the wiring harness side look like?

 

if you want to know the engine temp best to install a aftermarket gauge. stock temp gauge is not remotely reliable along with the amp gauge barely ever moving.

 

@"HeyYou":
It is a single wire connector with a rubber elbow connector onto the switch/sender.


Where did you wire in the temp gauge sensor? I know there are two sensors in the coolant block in the top of the motor. One with that single wire boot connector and one with the two wire pigtail connector. I am leaning towards installing aftermarket gauges.