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Surge tank and low coolant sensor

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I have looked at all the threads on the tank and sensor and can not seem to find an answer to my problem.

My low coolant warning light stays on all the time.

I have replaced the aged plastic surge tank with a new aluminum tank and Ford sensor.

Wired the Ford sensor leads together with the one wire coming from who knows where that was on the original sensor. 

I still have a nice bright low coolant light at all times.

Here is what I have done so far;

Unplugged the sensor and shorted the connector to ground---No change

Left the connector unplugged completely---No change

I can't seem to find where this sensor wire goes to in any of the prints. Does it go directly to the ECU? if so anyone know what pin it comes into the ECU on?

The previous owner (original owner) told me that it had not worked for several years he just kept track of the temp gauge and checked the level when he fueled up.

Any ideas out there?

2002 Monaco Diplomat ISC 8.3




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On my 2000 Diplomat it is wired directly to lamp on dash. Do you have wiring diagrams for coach ?  On later models of Monaco it is wired to ecm and will turn on the warning light. If you have low coolant light on dash then the ecm is not in play.

Bob U 2000 Dip



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15 hours ago, jacwjames said:

I "think" my 2002 has a Kysor low coolant module, see attached

My wiring diagram shows a "Low Coolant Module" that has a Low Coolant Probe wire coming to it and then it is wired to the light. 

I have no idea where the module is, my guess buried in the dash somewhere.

Low Coolant Module KYSOR ALARMS SERVICE AND INSTALLATION.pdf 4.01 MB · 12 downloads

Thanks I'll look for it.


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  • 3 months later...

Hey Cliff, this is Chris. You got the new tank and sensor from me. Connect one wire of the low coolant sensor harness to the wire coming from your coach (was previously hooked to old sensor) then ground the other wire from the sensor harness to a tank mounting bolt. Tank looks great by the way!

Edited by C-Low Fab and Performance
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That is the way I hooked it up. I also replaced the two lines going into the top of the tank, they were looking kind of poorly. 
Everything looks and works great just did a 1700 mile trip. 
that being said the low coolant light is still on. I’ve gotten in the habit of checking the level every time I fuel up.


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