99 regal 3.8 coolant level sensor issues

[veedubmechanic]

I have replaced the sensor and cluster and the light still comes on. I have made a new ground and light still says on. 12v to the sensor and 9v on the ground side. When unplugged the light goes off.
I checked the coolant for voltage and found .02v.
Any hints on this? Flushing coolant tomorrow. Intake is seeping very little and coolant looked fine.

[DeltaP]

Is there a resistance value for that sensor?

[veedubmechanic]

I checked new and old. Both no resistance.

[DeltaP]

Time to hit the schematics I guess.

[Tech II]

There is no resistance to it, it is just a switch...it's either open or closed(this happens when coolant is low).....

This is how you check the circuit.....disconnect harness from the the switch, light goes out......jumper the two wire harness together, light comes on......so if you disconnected the switch, and the light went out, you have a bad level switch, or if you put a new one in, and it was initially good, and now it's bad, it's because the coolant is contaminated, or the level is low in the radiator....

One thing bugs me.....12v to the sensor and 9v on the ground side.

If you got these readings from the harness, with it disconnected, you should read 12v to the switch, but there is no way there should be 9.0v on the ground side.......

[DeltaP]

A schematic would have showed me it was a switch. I didn't get the 9v either. Didn't figure the contaminated coolant. I should have,that makes sense.

[veedubmechanic]

I had the harness plugged in to the sensor checking ground voltage (made new ground)
I drained the coolant tonight. I will flush it tomorrow. I think the intake leak contaminated the coolant.

Side note I plugged the harness into a new sensor and filled the dish with water and the light stayed on..?

[veedubmechanic]

Just as an update:
I flushed the system clean.
I ran the car with water in it while the hose was in the radiator running and the light stayed off.
I drained it and topped off with dexcool and bleed the system and the light stayed off.
Let the car sit outside for 3hours and turned the car on and the light came back on. Looks like the Intake gaskets are leaking causing enough air In he system or oil to mess the sensor up.

[Tech II]

If you have air in the system, this can make the radiator level low enough to trip the switch.....

[veedubmechanic]

Just as a resolution to this, I found the brand new sensor was bad. I flushed the system a second time with chemical cleaner an the light came on. Replaced the sensor with an ac Delco part and good to go.
The little rod in the new sensor was bent. Cheap Chinese parts.

Also afterwards ended up replacing the lower intake and bypass hoses because customer didn't want to deal with it again.

[vdtken1]

Reading these threads I think I know why mine keeps going on even though I replaced it with one from the junk yard. I had the typical intake manifold leak on my Regal and used a sealant that has little copper particles in it to plug the leaks. Fixed the leaks but must be changing the resistance on the sensor making it look like coolant low!
That's why flushing the coolant probably fixed the problem for some of you other guys and not the new sensor.

Good Luck!

Ken

[Tech II]

If you have contaminated coolant, installing a new sensor, may work for a short time........then the sensor becomes contaminated again.....then the coolant has to be flushed....the usual life of the coolant is 5years/100K miles, whichever comes first.....so a '99 should be on it's third flush by now.....but I can almost guaranteed, most have never been flushed....just dumping the radiator is not a complete flush......