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


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While doing a little cleaning of the engine compartment after a recent ride down a very dusty road, I stumbled upon what appears to be a sensor mounted into the block right at the exhaust manifold.  What has me baffled is that there is no wiring connector attached to it.  Any ideas of what it is?  See pic below.

 

Unknown Sensor.jpg

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@DavidL @OhReally Thank you for your responses.  I did a quick look for a loose connector and didn't see anything.  I will do a more thorough look today.

 @Gary Cole   Do you know where this would alarm?  Do you have a dash indicator for this?  I do not. 

The interesting thing about this is I looked on QuickServe at my engine diagram, and there is no sensor shown on the engine in this location.    I also did a search on QuickServe for Temperature Sensor and nothing shows up for this sensor. 

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Hi Bill, I have 2 questions.

1.  Are you currently getting a reading on your coolant/engine temp gauge on the dash?

2.  Is there a similar looking sensor (with wires attached) within 4-5 inches of your thermostat housing?

If the answer is "yes" to either question, I would be inclined to go with what Gary said above.

Just my "2 cents"

Carey

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36 minutes ago, Idoc57 said:

1.  Are you currently getting a reading on your coolant/engine temp gauge on the dash?

Yes - I have constant engine coolant temp on my Aladdin display.

39 minutes ago, Idoc57 said:

2.  Is there a similar looking sensor (with wires attached) within 4-5 inches of your thermostat housing?

Yes - it is located in the location you mention and where the QuickServe engine diagram shows where it should be.

@Gary Cole and @Idoc57 I am going to then assume since this is Monaco Specific, AND since my dash does not have an indicator for this, it was installed by Monaco, but no wiring connector since it is not being utilized by my coach?  I am also thinking that maybe the Monaco factory bent the terminals indicating they were not to be used.  I say this because the bends appear to have been manually made in the middle of the terminals.  Just guessing on this though.

 

 

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My ‘05 Cayman has that sensor in use for the dash coolant temp gauge.  This coach does not have the Aladdin system.  

On my maiden voyage home with the rig, the coolant temp gauge was constantly flying all over the place.   I pulled over to quickly check the wiring at the gauge for anything obvious and found nothing.   It was when I pulled the engine hatch that I noticed the sensor and what I would assume was a handyman repair to those wires as the spade connector used didn’t match any others and the wiring “just” reached.  Anyways, put new spade connectors on and the gauge has read steady since.  
It must be Monaco specific, as the Bluefire still reads coolant temp fine with that gauge disconnected. 
 

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31 minutes ago, 96 EVO said:

 

Odd your Windsor didn't come with a dash coolant temp gauge.

 

I do have a dash temp gauge that works fine and follows the Aladdin read out.  What I do not have is an indicator lamp for high temp.  I may have misinterpreted @Gary Cole when he said he had an indicator that it was a lamp and not a gauge.   Either way since I have both the dash gauge and Aladdin this one does not seem to be part of my setup.  

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11 hours ago, Bill R said:

I do have a dash temp gauge that works fine and follows the Aladdin read out.  What I do not have is an indicator lamp for high temp.  I may have misinterpreted @Gary Cole when he said he had an indicator that it was a lamp and not a gauge.   Either way since I have both the dash gauge and Aladdin this one does not seem to be part of my setup.  

Both the dash gauge and the Aladdin are getting engine temp data from the engine ECM on the same data bus.  The same data would be on the diagnostic port under the dash.

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9 hours ago, Happycarz said:

Bill, mine has a pipe plug in that position, no sensor.

Harry - thanks, then probably not originally intended for my model coach either.

51 minutes ago, Frank McElroy said:

Both the dash gauge and the Aladdin are getting engine temp data from the engine ECM on the same data bus.  The same data would be on the diagnostic port under the dash.

Exactly Frank - I have what is needed via the thermal sensor by the thermostat which is the engine temp for the ECM.

40 minutes ago, Michael Powell said:

Usually 2 pin connectors are a switch type sensor either engine hot light or telling the ECM engine is at operating temperature...

Just a thought...

Michael - I was thinking also this may be more of a switch type thermal sensor.  Same conclusion though, it is not needed since ECM is already monitoring and I have no engine hot light.

25 minutes ago, Jdw12345 said:

Is it possible that the previous owner had a stand alone temp gauge……

Jeff - who knows, but very possible.  Thanks,.

 

MY FINAL CONCLUSION - Thank you everyone for your responses.  It seems unanimous that this sensor is not required for my coach.  Still a mystery as to why it is there, but not needed to really know why. 

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Bill,

I was going to respond earlier, but been away from coach and didn't think I had any pictures with me.  However,  I did find a picture that might help you.  Once I'm back at coach, I can give you more details.

The white horizontal wire next to the blue hose goes to the sensor in question.  It's a single wire.  Sensor your mentioned  has 2 post, however. From there the wire goes into the wire loom running across the engine (left to right) and turns an goes forward along a frame rail with a bunch of other wires.  I know this is all OEM.

If I were you, I think I'd cut those wire ties holding the bundles and see if you can find a single wire in there that's been abandoned.   I could be  wrong, but I think that sensor is the high temp sensor that will illuminate an idiot light on the dash.   So Aladdin or gauges wouldn't be effected. 

thermostat.jpg

Edited by windsorbill06
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Bill R, I have a 05 Windsor and I think the 06 was likely a carryover from the previous year, since Monaco was eliminating the Windsor at that point.

So, I took a picture of my sensor, and as you can see it has 2 wires, not one. As WindsorBill posted, it goes into a big wiring bundle closer to the coach rear and then the bundle appears to go forward.  You can see the bundle on WindsorBills picture post.

I would add one more possibility to the idiot light idea.  Mine, and I think yours,  has/had a Sauer Danfoss fan Controller.  I’m told that the fan controller communicates with the ECM to regulate fan speed.  So, this could be a temp sensor for the ECM, for that controller.  If your coach has been changed from this controller to a wax valve setup, someone might have eliminated the sensor.  It might not affect operations, since I think there are multiple sensors. But, you might find wire ends on the back side of that cable bundle.

3BE36161-4625-48ED-8FB0-A5755881BE74.jpeg

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6 hours ago, Frank McElroy said:

Both the dash gauge and the Aladdin are getting engine temp data from the engine ECM on the same data bus.  The same data would be on the diagnostic port under the dash.

data bus?

Frank do you know which ECM pin # provides output to the dash gauge? I don't see it on my schematic. My original dash gauge was analog (12V + with variable resistance sensor providing a ground path) and not digital. I never figured out where the gauge got its non- standard resistance ground  from when I replaced it. There is another sensor on the front of my engine however I cannot access it as it is completely  buried under engine accessories. So I installed a new sensor which matched the new gauge at cylinder #6  when I replaced it.

Bill I jumped the conductors at my sensor to verify that it is indeed the high temp light at the dash. It is a N.O. switch as someone suggested. 

 

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If you go the Cummins Quickserve site, create and account and register your engine you will find a electrical schematic of the EMC outputs and how it interfaces with the chassis side.  

It also has the pin wiring so you can determine which one to test.

Edited by jacwjames
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1 hour ago, Gary Cole said:

data bus?

Frank do you know which ECM pin # provides output to the dash gauge? I don't see it on my schematic. My original dash gauge was analog (12V + with variable resistance sensor providing a ground path) and not digital. I never figured out where the gauge got its non- standard resistance ground  from when I replaced it. There is another sensor on the front of my engine however I cannot access it as it is completely  buried under engine accessories. So I installed a new sensor which matched the new gauge at cylinder #6  when I replaced it.

Bill I jumped the conductors at my sensor to verify that it is indeed the high temp light at the dash. It is a N.O. switch as someone suggested. 

 

This varied over the years where the gauge clusters although looking analog were actually digital stepper motors controlling the dials.  Not sure how much of you gauge cluster and warning lights get their multiplex signal over the J1939 or J1708 or older J1587 data bus.  The multiplex signal over a single pair of twisted wires handles all communications between the engine, transmission, transmission control pad, antilock brakes and dash gauge cluster computers.

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Well, well, well.  @windsorbill06 after telling me offline that you think you had a temperature sensor in the same location, I went to the coach and did exactly as you suggested, and look what I found.  I had to dig deep in the wire looms as it was tucked completely behind all of the other wire looms.  See pic.  Two white wires that appear to have heat damage at the end and also seem to have had spade connectors attached at one time.  The deteriorating tape around it seems like this was done many years ago.

So now a few questions:

1) Are those the wires for the sensor?  @David White just now reading your post, thank you for the pic!!  So now I am confident these are the wires.  But now as you mention, is it a warning light, or an ECM input for the SD Controller? 

2) Is it for a dash warning light?  My dash warning lights do not have a "high temp" light.  The only lights that could be in question are "warning", "check engine" or "stop engine".  All other lights are obvious to what they are.  Reading the manual it does not give any idea.  Looking at the dash wiring diagram it doesn't indicate a temp sensor input.  And my chassis wiring diagram is unreadable.  @Gary Cole Yes when I put my VOM on the sensor it show no continuity.  So is the name on your dash light "high engine temp"?  I do not have any warning light with that title.

3)  Is it for ECM input? I do not have a wax valve but SD controller.  When I bought the coach 1 1/2 years ago, the fan was running wide open.  In troubleshooting the SD controller, it did seem to be bad as the input to the SD controller from the ECM seemed to be reading correctly but the SD control board was sending a constant wide open signal to the variable control valve.  I bypassed the SD control board and now use a motor controller to take the ECM input and then control the SD proportional valve.  Works like a champ.  @jacwjames I have looked on QuickServe at my engines ECM wiring.  There is the Cummins side input for Engine Coolant Temp.  That is what goes to the Aladdin and gauges as my continuous reading for Engine Coolant Temp.  For the OEM input side, the only related inputs I see is  "OEM Temperature Sensor" which I am assuming is the Ambient Air Temp I see on the Aladdin ECM data.  And then there is a "Switched Outputs Temperature Sensor".  Do you have any idea of what that is?

4) How should I proceed?  This is where I am leaning heavily on the experts in this forum to guide me.  I am tempted to jump the two wires together like @Gary Cole did and see if a dash light comes on?  Thinking that if this is a temp switch then that is all it would be doing.  BUT........I do not want to take any chances if this is an ECM input, which is not clear to me.  Does anyone see a risk in connecting these two wires to see what happens?  My VOM does not show any voltage on these wires when the ignition is on.

Thank you everyone so far for their input.  I thought I had this solved, but now that I found the wires, time to continue to figure this out.

 

 

 

Coolant Temp Switch Wires.jpg

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1 hour ago, Bill R said:

 

4) How should I proceed?  This is where I am leaning heavily on the experts in this forum to guide me.  I am tempted to jump the two wires together like @Gary Cole did and see if a dash light comes on?  

 

 

 

Coolant Temp Switch Wires.jpg

Sure!

What could go wrong 😂!!

Seriously, you appear to be a operator that keeps an eye on your vitals. If it does feed an idiot light, do you really need it?

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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.

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

I only have 1 wire connected to the sensor terminals.  I know it came from Monaco this way.  I grounded out that wire and I DO NOT get any idiot light on dash with engine running or not.  There is no continuity between either terminal and the sensor body with engine cold.  .  I've never overheated. but possibly, in that scenario,  it will send a signal to ECM to derate engine, IDK.

Why some have 2 wires and I have one, and some have none,  is also interesting.    

sensor behind thermostat.jpg

Edited by windsorbill06
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