Cat engine temp sensor

Your not a knob by any means.. So heres how I check the single wire sending units
Use your multi meter set it to read ohms which the symbol alittle like a upside down horse shoe.. put 1 probe on the body of the sending unit and the other probe on the terminal the wire attaches too then see what you get for a reading if my memory is right it should read around 200 ohms give or take some if you don't get a reading or very low reading like 30 or 40 ohms then your sending unit is bad.. Maybe somebody will jump in that knows exactly what the reading should be but if its low by meaning 60 or less or next to nonthing that means its not working... this is just a Layman's version .. Iam sure there's people on here that can be more in detail.. best of luck to you

 

Do I remove the sensor, or can I leave it in the thermostat housing?

 

You should be able to leave it in the housing

 

The mystery thickens, tested the sensor with an ohm meter, appears to be ok. Tested the water temp gauge by moving the plug from the oil temp gauge to the water temp gauge, and gauge moves showing the oil temp.
Now noticed when I plug in the water temp gauge, the needle drops below 100, unplug it and comes back a little from ‘bottoming out’, plug back in, gauge bottoms out below 100 again.
This truck originally had a mechanical gauge, do I need a resistor of some sort?
Is possible I have a sensor designed for a ‘positive ground’ vehicle?

 

I didn't go back thru you other posts but did you check you sending wire from your gauge to the sending unit to make sure it didn't have a break or short in it by running a continuity test ??? And have you checked to make sure you have power going to your water temp gauge ??

 

Everything checked out. Finally removed the brand new sensor, went to the boneyard, and got an oil temp sensor from a blown engine, installed it in place of that new one, now everything works. Called the supplier that I bought the new sensor from, they suspect a ‘mis-package’. I might have a water temp ‘switch’ instead of a ‘sensor’.

 

Glad to hear you got it working !! Thanks for the update too
I've got a project truck in my shop that 4 out the 5 temp gauges are not working the wiring in this truck is a disaster