400 ISL - What is this sensor? No wiring connector attached.

[Bill R]

17 hours ago, Ivan K said:

I would test resistance of the sensor between its body and the in dividual connectors. Most 2 wire temp sensors I am familiar with send ground to the lamp on one and proportional ground to gauge.

Ivan - yes, one of the connector wires goes to ground.  I get continuity with the engine block.  Also, one of the temp sensors is grounded as well.  When I connect the right spade of the temp sensor in the pic I get continuity with the engine block as well. Is this what you were expecting?  So how would the two wires be connected to the temp sensor.  I assume that the grounded spade on the temp sensor to the grounded wire?

 

[Bill R]

1 hour ago, windsorbill06 said:

 

I did a little more research now that I'm back home with coach, but no real answers.

 

Bill - I went ahead and connected both wires with ignition on but engine off, and no idiot light illuminated.  I then started the engine and still no idiot light.  I also checked the fan speed and it was at idle speed with wires connected.  No change in fan speed when I disconnected the wires.  
 

So this temp sensor does not go to an idiot light, and does not seem to go to the ECM for engine fan speed or engine shutdown.   I am concluding again that this was installed either for a coach like @Gary Cole 2005 Diplomat that had a high temp idiot light.  Or maybe for some other field test purposes.  But as far as I can tell for our 2006 Windsors it is not being utilized.  

[windsorbill06]

1 hour ago, Bill R said:

Bill - I went ahead and connected both wires with ignition on but engine off, and no idiot light illuminated.  I then started the engine and still no idiot light.  I also checked the fan speed and it was at idle speed with wires connected.  No change in fan speed when I disconnected the wires.  
 

So this temp sensor does not go to an idiot light, and does not seem to go to the ECM for engine fan speed or engine shutdown.   I am concluding again that this was installed either for a coach like @Gary Cole 2005 Diplomat that had a high temp idiot light.  Or maybe for some other field test purposes.  But as far as I can tell for our 2006 Windsors it is not being utilized.  

I tend to agree. 

Ha!   Maybe we can use it as a fluid sampling port? 

[Ivan K]

1 hour ago, Bill R said:

Ivan - yes, one of the connector wires goes to ground.  I get continuity with the engine block.  Also, one of the temp sensors is grounded as well.  When I connect the right spade of the temp sensor in the pic I get continuity with the engine block as well. Is this what you were expecting?  So how would the two wires be connected to the temp sensor.  I assume that the grounded spade on the temp sensor to the grounded wire?

 

Well, it isn't what I expected, not for a switch, makes no sense to have a grouded pin. But, for a gauge signal, yes it could be a sender if there is a temp dependent resistance between the two pins, one of which is grounded. I measured 2.2k on a random sensor in my shop, room temp. One of your abandoned wires would also have to have a positive potential - not necessarily enough current for a test lamp unless LED. Something like in the picture. But as you said, it may not even be applicable to your coach if there is no missing function. I myself have used an old sensor just as a plug when testing engines on a test stand sometimes just because it was handy...who knows.

[Bill R]

1 hour ago, Ivan K said:

Well, it isn't what I expected, not for a switch, makes no sense to have a grouded pin.

Thanks Ivan - Yes it didn't make sense that the pin is grounded. 

1 hour ago, windsorbill06 said:

Ha!   Maybe we can use it as a fluid sampling port? 

Great idea Bill!

[Jdw12345]

If you don’t have a wet compartment heater it could be used as a port for a heat exchanger in the wet compartment.

[96 EVO]

May be a bit costly thou running an ISL to keep the wet bay warm 😀.

[windsorbill06]

3 hours ago, 96 EVO said:

May be a bit costly thou running an ISL to keep the wet bay warm 😀.

I would hope he's talking about when driving down the road.

 

Edited March 10, 2023 by windsorbill06

[KevinG]

Any chance you can make out the numbers on the body of the sensor?. Also that pin could be seen ground because the sensor has failed and maybe why it was disconnected.  

[windsorbill06]

A question for this group.  

Will the ECM  reduce power to the engine when it sees an overheat condition?  Or just an idiot light and gauge indication?

[Frank McElroy]

Depending on the severity of the overheat, the engine will derate and possibly trigger a stop engine warning.  The overheat will also be recorded in the engine abuse history report that can't be erased.

[Bill R]

6 hours ago, KevinG said:

 

Any chance you can make out the numbers on the body of the sensor?. Also that pin could be seen ground because the sensor has failed and maybe why it was disconnected.  

 

Would probably have to pull the sensor to read anything.  I agree that the grounded terminal could indicate a bad switch.  Regardless, it appears to have been removed for many years and not affecting any engine parameters or alarms.  Jumping the wires also shows no alarms or engine performance changes.  

[windsorbill06]

Frank,

Reason I asked, could this sensor be the one to trigger the ECM in an overheat condition?    It's pretty difficult to shop test  it, but I suppose a person could ground the wire and drive the coach reasonably hard and see if the ECM derates.

I suppose this test would record an 'overheat condition' and that might NOT  be a good thing, even though it really didn't happen. 

  

Edited March 10, 2023 by windsorbill06

[Frank McElroy]

Your ISL only has one temperature sensor.  If your dash gauge is working, the temp sensor is working.  I looked at the ISL CM850 engine wiring diagram and the temp sensor has 2 wires and neither one is grounded at the sensor.  If like you say, the sensor pins show resistance to ground, it's likely a bad sensor or a case where a previous owner added that sensor to fix a fan control issue that didn't work and they never removed it.

Take a look at quick serve that is specific to your engine serial number and you will see the location of your coolant sensor and likely no sensor in the location your seeing the disconnected sensor.

However, as others have said, this could have been a Monaco add on.  If one spade is grounded, that's why only the other spade is used.  Does your owners manual have a dash high temp light?  With your engine year, this could be a control for the fan that might have been converted to a wax controller.  On newer engines like mine the fan control is direct from the ECM.  The ECM records abuse history from the same temp gauge sensor you see on the dash.

[David White]

3 hours ago, Frank McElroy said:

Your ISL only has one temperature sensor.  If your dash gauge is working, the temp sensor is working.  I looked at the ISL CM850 engine wiring diagram and the temp sensor has 2 wires and neither one is grounded at the sensor.  

Frank, you know much more about this than me, but I have that same engine in my 05 Windsor and it came from the factory with the sensor noted and 2 wires. I put a photo and comments in my earlier post.  It could be my only sensor, and if so it should be working to prevent problems. Or, it could be a second sensor.

I had questioned where or not it fed the temp to ECM for the Sauer Danfoss fan controller.  I would think only one sensor would be needed.

[Frank McElroy]

47 minutes ago, David White said:

Frank, you know much more about this than me, but I have that same engine in my 05 Windsor and it came from the factory with the sensor noted and 2 wires. I put a photo and comments in my earlier post.  It could be my only sensor, and if so it should be working to prevent problems. Or, it could be a second sensor.

I had questioned where or not it fed the temp to ECM for the Sauer Danfoss fan controller.  I would think only one sensor would be needed.

This is what a Cummins OEM temperature sensor looks like and it is mounted below the thermostat housing.

Early ISL engines were not as sophisticated in direct electronic control of the fan via the ECM like my ISL.  From Insite software I can directly control any fan speed from 0-100% in I think 5-10% increments.

My thinking is that Monaco added a temp sensor most likely for fan speed control.  If a wax controller was installed, then you wouldn't need a separate temp sensor.

[David White]

8 hours ago, Frank McElroy said:

My thinking is that Monaco added a temp sensor most likely for fan speed control.  If a wax controller was installed, then you wouldn't need a separate temp sensor

Frank, I think you are correct.  My limited knowledge comes from a time when Monaco brought parts to MI rallies and we purchased and they would install free. I had the fan controller replaced and remember the tech telling me something about a sensor and the controller. That might be what he referenced.  Thanks 

Edited March 11, 2023 by David White

[Happycarz]

Maybe opening up the loom to look for labeling on the wire might help. Sorry, but don’t know what year Monaco started labeling wires. My coach, manufactured in May 2007 has white wires with labeling.
Just a thought.

[Bill R]

@windsorbill06 My take is this is a Monaco installed temp switch for a high water temp light.  @Gary Cole confirmed this on his coach by jumping the sensor switch and seeing his high water temp light illuminate.    Our 2006 Windsor's do not have this light on the dash.   Dynasty manual below shows this dash indicator.

 

@Happycarz Harry how would the wire numbering help out?  I am not familiar with the nomenclature of the labeling for the wires? I will look, as I can identify in the loom how they are labeled.

 

[Happycarz]

Monaco, on my coach, was nice enough to label what the wires do, and sometimes where they connect to the FRB. Some of the wires give the description of the device it goes to with the circuit number.   

Below is some examples from my coach.  

 

 

[Bill R]

@Happycarz Harry - the wire was labeled.  "Water Temp Sender"  I am not surprised that is what it is labeled, but where was is it going?  It travels to a larger loom headed to the front of the coach.  I have checked all through my wiring diagrams with out finding this wire.  Also, looking at my ECM data input from Insight, there is only one engine coolant temp input and that is already inputted from a temp sensor installed by Cummins down by the thermostat.  Still thinking this was a idiot light input that my coach does not have.  The other wire is connected to ground, with a resistance of about 15,000 ohms.  Nothing labeled on it though.

 

Edited March 15, 2023 by Bill R

[Happycarz]

It could go to nowhere.  I have both wiring and a relay for a tag axle I don’t have. Very frustrating. 
 

Does that 145 show any of the schematics?  

[96 EVO]

Maybe a harness from earlier years that had the idiot light 🤔.

[Gary Cole]

1 hour ago, Happycarz said:

It could go to nowhere.  I have both wiring and a relay for a tag axle I don’t have. Very frustrating. 
 

Does that 145 show any of the schematics?  

 

Harry when did you notice that your tag axle was missing?😁

Wiring harnesses are largely generic by necessity. You people with shorter coaches wondering why you have so much extra length coiled up. Cause they long enough to fit a 45 footer and have conductors for every available, sometimes fanciful,  salesman's option.

Edited March 15, 2023 by Gary Cole

[Happycarz]

Gary, when I toured the Monaco Indiana plant, an again when I toured the Oregon plant, the folks in the loom making area, were emphatic that each harness was for a particular coach.  

At least the nice folk there were consistent with there lies and screwups, by installing a weight placard for a coach with a tag axle on my wall. They were in “transition” when I asked for a correct one. They told me they couldn’t issue corrected one. So, I asked for a tag axle. LOL! 

To remedy the situation, I took a picture of my buddy’s Scepter placard and using Word, made one very close to my buddy’s.  (His coach was built 6 weeks before mine.) No one would notice the new one not being an original. And, the next owner won’t be confused.