low coolant level/light

[tlevan03]

Folks,
My low coolant light has been on for a few months and I decided to change the sensor out yesterday. The coolant level has never been low so i figured the sensor is the culprit. I took my inner fender out and changed the sensor. I was expecting a coolant bath but the sensor came out dry. Is that normal? I would assume that it is a wet sensor, but I pulled the old sensor and not one drop came out. I did have the reservoir cap loose to relieve any pressure. This has me really stumped, and my light is still on. Any insight is appreciated. Thanks

 

[Ltngdrvr]

The sensor works by completing the circuit when the end gets wet, so if the system is full there should be coolant come out when you remove the sensor. If it was dry, then that is why the warning light was on.
So, sounds like the cooling system is actually low, not a bad sensor.

 

[BarryG]

While this post is of no real value to your question on my 2017 i had the light go on within about a year. Added some coolant and it stayed off until I had the water pump recall done. Then it came on on my way home (thanks dealership for filling it back up after it hit operating temp, not). I added more when I got home and it has not come on since, been at least a couple years now.

 

[AH64ID]

Folks,
My low coolant light has been on for a few months and I decided to change the sensor out yesterday. The coolant level has never been low so i figured the sensor is the culprit. I took my inner fender out and changed the sensor. I was expecting a coolant bath but the sensor came out dry. Is that normal? I would assume that it is a wet sensor, but I pulled the old sensor and not one drop came out. I did have the reservoir cap loose to relieve any pressure. This has me really stumped, and my light is still on. Any insight is appreciated. Thanks

Sounds like you are low on coolant.

 

[tlevan03]

Initially when the light first came on the coolant level was right below the "max" line. I topped it off to level and the light stayed, i added just a little more and it would boil over when towing. There is coolant in there, i will verify again this afternoon. Would there be anything that would prevent coolant from getting to the sensor (i.e. baffles, or passages within the reservoir)?

 

[Cummins12V98]

What year is your truck? Does it have the pipe with the plug to allow coolant to completely fill.

 

[tlevan03]

2017. I believe you're referencing the hard line by the valve cover on the exhaust side? yes I think it does.

 

[Ltngdrvr]

Tank on my truck is very discolored, I shine a flashlight down through the cap opening to see the level of the coolant.
Fill line is basically right at the parting line between the top and bottom half of the tank.

 

[AH64ID]

Would it boil over, or expand and overflow?

 

[tlevan03]

Expand and over flow because I added too much to it.

Would it boil over, or expand and overflow?

 

[Cummins12V98]

2017. I believe you're referencing the hard line by the valve cover on the exhaust side? yes I think it does.

I don’t think your truck has the pipe so it should fill completely from the tank.

 

[Cummins12V98]

Tank on my truck is very discolored, I shine a flashlight down through the cap opening to see the level of the coolant.
Fill line is basically right at the parting line between the top and bottom half of the tank.

mine has been hard to see fill level also. Light is a good idea.

 

[tlevan03]

there’s plenty of coolant in there. Just above the seam

 

[tlevan03]

this is how much I was able to siphon out and then filled it back up. Light stayed on.

 

[AH64ID]

Is there enough slack in the harness to test the sensor with it removed?

 

[tlevan03]

Is there enough slack in the harness to test the sensor with it removed?

I could probably cut some zip ties to get it in coolant. But there was almost a gallon in the reservoir so why was the sensor dry and nothing spilled out?

 

[AH64ID]

I could probably cut some zip ties to get it in coolant. But there was almost a gallon in the reservoir so why was the sensor dry and nothing spilled out?

I would try that, and maybe see what it takes to get coolant to come out the hole with the sensor removed.

Can you see anything broken or blocking the hole?

 

[tlevan03]

I would try that, and maybe see what it takes to get coolant to come out the hole with the sensor removed.

Can you see anything broken or blocking the hole?

I couldn’t when I emptied it out. I’ll have to try later on and get the inner fender back out and go from there. I wish I had a spare reservoir to look at and see what could be in that area that’s causing the sensor not to come into contact with coolant

 

[gsbrockman]

Sediment and discoloring of the tank is most likely your problem, @tlevan03 .

I went through a similar issue with my 2018 RAM 4500. Contrary to popular belief, the sensor is based on something along a photo eye theory of operation.

I replaced my sensor and nothing changed. Ended up replacing my very discolored reservoir, which included a new sensor. Problem solved....

 

[tlevan03]

Sediment and discoloring of the tank is most likely your problem, @tlevan03 .

I went through a similar issue with my 2018 RAM 4500. Contrary to popular belief, the sensor is based on something along a photo eye theory of operation.

I replaced my sensor and nothing changed. Ended up replacing my very discolored reservoir, which included a new sensor. Problem solved....

I’m pretty certain that’s the direction I’m headed. I can’t come up with any other trouble shooting ideas. Thanks