Testing Coolant level sensor

[Headnsouth]

My 98 Low Coolant light went on so I cleaned it and then it went to blinking. Its an original part so I replaced it and now its on constant. Is there anyway to test these sensors?

[Headnsouth]

I replaced the sensor again (under warranty) and I still have a Low coolant level light. What the? I haven't had any dex-cool in this van in 10 years been using regular glycol 50/50 mix. If I unplug the sensor I get no light which is just as good as a false reading.
Can someone explain why this is happening?

[Headnsouth]

I'm scratching my head here. I pulled the new sensor out again and stuck it a bucket of water and it still gives a low coolant light on the dash. Any ideas? What else controls this?

[Headnsouth]

Go the light to go out. I never turned on the heat so I guess there was an air bubble lodged around the sensor. That doesn't explain the sensor in the bucket unless straight water doesn't trip it.

[Headnsouth]

The light is back on.

[3100]

LOL give the sensor some time they are lazy, (sometimes will take couple of hours of driving to turn itself off)

also check that black and yellow wire is not shorted to ground. Also disconnect connector of the sensor use multimeter to test resistance of the sensor with full reservoir of coolant. The sensor should read open if not then you have short soemwhere.

do this test, then tell me results so we can proceed with other tests if necessary.

[Headnsouth]

Originally Posted by 3100

LOL give the sensor some time they are lazy, (sometimes will take couple of hours of driving to turn itself off)

also check that black and yellow wire is not shorted to ground. Also disconnect connector of the sensor use multimeter to test resistance of the sensor with full reservoir of coolant. The sensor should read open if not then you have short soemwhere.

do this test, then tell me results so we can proceed with other tests if necessary.

I'll check the sensor and wires but its the second brand new sensor i installed with the same results.

[Headnsouth]

I checked the sensor and its test's good. Traced the wires back to the fuse box and pulled the fuse block connector on the back and it shows open back to the sensor. So I thought I might have a bad relay. Swapped them with the exact duplicates in the FB and still I get the low coolant light.
So I guess the short is somewheres else.