2005 Holiday Rambler "STOP" engine light on dash comes on and goes into limp mode

[robert98506]

2005 Holiday Rambler "STOP" engine light on dash comes on and goes into limp mode.
Cummins engine ISC-330,
I took the coach to Cummins engine service center, they read the code and said the only reason "STOP" engine light on dash comes on is if you are low on coolant or the sensor unit is bad.
I changed the sensor unit and it cured the problem for a while, but then came back.
I changed the sensor unit twice, and after a couple months the problem comes back.
The sensor unit is a Ford part, XC4Z-10D968-AA
The sensor unit goes in the pressurized overflow unit of the radiator.
I can unplug the sensor unit, but then the Service Engine light on the dash comes on.
If anyone knows of a post that someone else has posted before, or how I can get to that post, let me know.
Thank you very much for your time.

[nvs4602]

[QUOTE=robert98506;4461187]2005 Holiday Rambler "STOP" engine light on dash comes on and goes into limp mode.
Cummins engine ISC-330,
I took the coach to Cummins engine service center, they read the code and said the only reason "STOP" engine light on dash comes on is if you are low on coolant or the sensor unit is bad.
I changed the sensor unit and it cured the problem for a while, but then came back.
I changed the sensor unit twice, and after a couple months the problem comes back.
The sensor unit is a Ford part, XC4Z-10D968-AA
The sensor unit goes in the pressurized overflow unit of the radiator.
I can unplug the sensor unit, but then the Service Engine light on the dash comes on.
If anyone knows of a post that someone else has posted before, or how I can get to that post, let me know.
Thank you very much for your time.[/QUOTE

How long has it been since the coolant system was flushed and changed? A lot of problems can come from old worn out coolant.

[8.3Oilbuner]

Good morning Robert98506; Hi from up the way here in Auburn and just got finished reading your post. I have the same low coolant sensor that was installed in my 01 Windsor along with the new nylon expansion tank and a new harness for the sensor before I bought the coach back in 2015. I personally have not heard about any bad Ford low coolant sensors! First I would try to eliminate that the sensor is the problem. Not too much to go bad in that sensor. The two metal strips separated by a piece of plastic along with the outside electrical connections is all there is to that sensor. The circuit makes it's connection in the coolant. Low coolant breaks the connection thus turning on the low coolant light on the dash. One wire on the sensor goes up to the dash and the other goes to ground. It could be possible that the harness is not making connection after a while and when you unplug it to replace the sensor everything works for a while. It is my opinion that you have another problem beside the sensor. I would jump the terminals in the harness for a while and see if the light comes on. If it does, something is wrong in the harness or somewhere after the harness, ground or poor connection to the harness. Sorry, that's all I can think of right now. Let us know what you find. Good luck!

[robert98506]

Originally Posted by 8.3Oilbuner

Good morning Robert98506; Hi from up the way here in Auburn and just got finished reading your post. I have the same low coolant sensor that was installed in my 01 Windsor along with the new nylon expansion tank and a new harness for the sensor before I bought the coach back in 2015. I personally have not heard about any bad Ford low coolant sensors! First I would try to eliminate that the sensor is the problem. Not too much to go bad in that sensor. The two metal strips separated by a piece of plastic along with the outside electrical connections is all there is to that sensor. The circuit makes it's connection in the coolant. Low coolant breaks the connection thus turning on the low coolant light on the dash. One wire on the sensor goes up to the dash and the other goes to ground. It could be possible that the harness is not making connection after a while and when you unplug it to replace the sensor everything works for a while. It is my opinion that you have another problem beside the sensor. I would jump the terminals in the harness for a while and see if the light comes on. If it does, something is wrong in the harness or somewhere after the harness, ground or poor connection to the harness. Sorry, that's all I can think of right now. Let us know what you find. Good luck!

I have jumped the terminals and the "stop" light on the dash goes out, but the "check engine" light comes on. I drove it over 500 miles with jumper on and the "stop" light never came back on. So I do not believe it is in the wire harness. I traced the wires back as far as I could and they looked good. I checked with a ohm meter and one side is grounded. I put a 33K resistor in place of the sensor and now the "stop" & "check engine" lights do not come on. I Know I do not have the low coolant level protection now, but I will try It for the time being. If any one has any other solutions please let me know. Thank you.