Low coolant warning light and bell...

I have a 2006 volvo tractor and dash shows low coolant and it shuts off.
I replace the coolant level sensor and problem remains. I inspect the wiring to the connector and it does not show any signs of damage. Any suggestions as what to do next?

 

Did you trace wiring all of the way to ECM?

 

Prostar I used to drive for a company used to do that. It ran low on coolant once and, after filling, the idiot light never went off. A few taps with the handle of a screwdriver dislodged the air bubbles....

 

Is it 2 or 4 wire level sender?

 

Having same issue now. 18 579. Replaced sensor was good for 3 days. Acted up yesterday. Replaced sensor again. 50 miles later coolant light on again. It was triggering the dpf filter gauge to read full as well. Unplug sensor that code goes away. Today nothing so far. Wiring looks ok until it disappears into loom with everything else top center of motor. Tank might be next because of magnet internally will get stuck. To be continued....

 

Dynamite that tractor. See if it rings on the way down. HA.

 

How do you remove the coolant sensor is it just the zip tie holding it on

 

I'd do what kwill710 sugests.
If it works with the 200k ohm resistor unplugged, leave it that way and watch the temp gauge from now on like the old timers did.
My T800 doest have a low coolant sensor so I keep a close eye on at temp gauge all day long. You have that and your sence of smell. Just the other day I noticed 1st a hot coolant smell, then a few minutes later I noticed when the engine fan came on my temp wasnt dropping back to 185 like it should. Instead it kept climbing.

So I pulled over and found a coolant line spraying a tiny stream.

To keep from losing more coolant I loosened the hose clamp and pushed the hose farther on the nippel.
I then cut 1/4 inch off the hose at a time and pushing the hose
on farther each time until I got the leak cut out of the hose while never taking it completely off.

I put 4 gallons of water that I keep with me at all times in the radiator to make it to the nearest parts store and bought 4 gallons of antifreeze. Of which I used 3.5 gal.

I did all that without calling a mechanic and never signing out on my hourly haul.

 

I have a 2016 T680 with a Paccar MX13. Best thing to do is to remove the sensor from the bottom of the surge tank. The sensor will pull out and will not cause a coolant leak due to removal. Leave the sensor connected to the harness, and place a magnet near the top. If the alarm stops, the sensor is bad. If the alarm keeps going, the surge tank is most likely bad. In my case the alarm became intermittent. It would stop for 10 to 15 minutes then start again. Bought a new sensor from Kenwprth for $150 and fixed the problem. The surge tank in non-serviceable so that would have sucked.

 

I have a 2019 T680 with the same problem. I hacked a solution to the problem with a magnet and 2022 version of baling wire. All alarm lights and sounds are off and truck runs fine. Just do your precheck and eyeball the antifreeze reservoir, keep an eye on your engine temperature gauge and use your nose to sniff out any antifreeze odor. You don't need no stinking low coolant sensor. Pics are attached.

 

I have a 07 Pete 379 with a Cummins CM870, wiring diagram says there should be a 2 wire connector, but I got a 3 wire setup.
A,B,C on one diagram says 5v on one of the ends but I got Voltage in the middle. Does'nt make sense to me. What is going on here? I have a metal tank and
I'm not really sure how a level sensor sends an oscillated signal back to the ECM, shouldn't it be yay or nay??

-Chris