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Warning - Engine Electrical Protection Cicuits


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On the 15 mi drive home from routine service, the warning light came on the dash.  See pics of manual #6..  Only service Items were Differential lube change and greasing all the grease points, drain fuel filter, drain air valves.  Temps were in normal ranges in the way home. Oil pressure good.  

Electrical protection circuits suggests what?  I guess I will need to go back and have the guy pull the Cummins cods(s) and hope thar points to the problem?

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Maybe the tech bumped a sensor and a terminal came loose....??  OR, he had to move a harness and the harness sort of "came apart".  IT HAPPENS, way more often.

I can't tell you for certain, but I THINK, that most of the signals to the instruments are GROUNDED.  So, is there is a harness with a bunch of wires from the front to the rear....and one wire was nicked or has "vibrated" and chafed or rubbed through the insulation....grounding it to the CHASSIS will definitely LIGHT UP A LIGHT.

I installed a Fire Protection system with a sprinkler head in the engine compartment.  They cylinder feeding it has to mounted....so I put it above the engine with bolts coming through the back wall of the bedroom closet.  I moved, gently....NOT YANKED, a harness for more clearance.  Once in....I didn't bother to relocated.

A few weeks later...what is THAT NOISE?  I had a "DOOR OPEN" light.  I fumed and chased and called Monaco...NO HELP.  Turns out that the main backbone harness for the Dynasty and is the same for the Camelot.  SO, I got a wire in that bundle that is NOT used...as I do NOT have generator slide or engine compartment or bay door switches.  BUT, the dash cluster, since it is used on a Dynasty, has the idiot light.  I even called Medallion and talked to them and they sent me the pin outs for the inputs.  I was ready to cut the wire....which was OBVIOUSLY GROUNDED...  

I went back to the engine...  I moved the harness back to it's original location...maybe 1" or so.... BINGO...NO ALARM.  That was in 2010....never got that light since then...

You DO need to know what the CODE IS....  so, I would have it scanned by a reputable shop, with the INSITE software...as well as the "Brains and experience" to interpret.  

COULD be a sensor that was flaky and it got accidentially bumped.  Could be a false positive...  Assume ALL your gauges are reading OK??

NOW, if the shop that DID the work has the Insite software, they can send out a mobile tech.  He can scan and diagnose on sight.  If all is well, as in you don't have an issue and it is safe to drive...then you can drive it back and have the issue fixed.  IF there is a SENSOR and it is in the vicinity of where they were working...  I would NEGOTAIATE a price for replacement.  MOST reputable shops, if they break something that was OK due to negligence or a pure accident, THEY FIX.... or at least all my UH OH's have been fixed by the servicing shop....

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My nextdoor neighbor owns a chimera trucking company and he brought home one of his $10,000 test sets.  Thank God cir great neighbors!  Turns out the only code is a coolant sensor issue, either low coolant or a bad sensor, or a short to ground on one of the wires.  I unplugged the sensor  and plugged it back in... same code.  Tomorrow I will stir the coolant just to confirm the level.  If that fails, it is back to the shop for further diagnostics. 

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My 2002 Windsor's original coolant level sensor was a long probe that stuck down from the top, it was a common problem of it causing a problem and you could pull it out and clean it and that would solve the problem

In ~2014 my surge tank started to leak (again) so I finally changed it to the newer style, which had the sensor mounted in the side of the tank.  This is a Ford type sensor.  On my the coolant actually closes the circuit for the sensor to ground and I have Kysor low coolant module that receives the signal and triggers the low coolant alarm but I'm not sure how that interacts with the engine warning light. 

If you have an electrical diagram it will show the low coolant sensor and how it is wired. 

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Mine has always been a side sensor, fist on the nylon/plastic tank, now in aluminum.  Wiring could be shorted, but first checking coolant, then sensor cleaning and perhaps replacement.  If that fails, the painful process of digging up a wiring diagram and tracing wires will commence.

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@jacwjames Yep, the coolant sensor is in such a confined space on the right side of the tank that I can't get a picture of it (to see the part number).  So I'll have to risk trying to remove it, OR, identify the part number for it from a 2008 Monaco Knight wiring diagram (searching now -- I think @myrontruex did give me all OneDrive files and it might be in those.

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Hey Steve. I just went through the same problem last week. It was also the oil pressure sending unit. Just the audible alarm was sounding. No lights on in the display. I ordered the sending unit and replaced it.all is good now. You need to get the exact part number. I tried with a recommended one first and it was wrong.beeper still sounded. Must be the 2 wire VDO. I'll post the entire VDO number as I pull my invoice. 

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Okay. Here is the information on the sending unit. I even read a thread that says others are also having problems with these if they get wet. Anyway,  it's a 2 wire sender. 1 wire for the gauge and 1 for the alarm. They are specific on how they go on. It's located just above the starter on the lower right side of the engine so very easy to get at. Check to make sure your tech didn't knock a wire off first then take action from there on what you want to do. I got mine at Summit Racing. They were the cheapest and very helpful to deal with. Cheers.

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  • 2 weeks later...

I pulled the coolant level sensor today and sure enough, the part number is PBT-GP30.  Previously, Cummins could not find that part, and said to check with the RV side, which to them meant chassis; Freightliner, Roadmaster, whoever.  I have an RR8R chassis, and Googling Roadmaster helped not at all.  I had previously googled PBT-GP30, and found numerous sources offshore, none of them claiming to be OEM.  I ordered from one that looked the least dicey today (fingers crossed).  We'll see what happens.  Oh, the sensor also had a embossed number in it:  070511.  That didn't yield anything on Google or Cummins Quickserve.  How can one small part be so hard to find? 

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  • 3 weeks later...

Well, the saga continues... checked the coolant level and it's fine.   Cleaned the sensor, and no change.  Replaced the sensor (very hard to confirm backward compatibility)... no go.  I started tracing the wiring (it's inside a cable sheath) and about 8" back from the sensor it routes under a 3/4" piece of plywood with a steel L-bracket that is clearly crushing the sheath and wiring.  In any case, it's impossible to see where the wiring goes without removing a fuel filter, power steering reservoir, coolant overflow tank, and more, then the bracket itself.  The alternative is to determine where the wiring originates and run new wires.  I am trying to find the coolant level sensor wiring diagram for the 2008 Knight if anyone happens to have one in file.  Thanks in advance.  

Steve P

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I wouldn’t think a low coolant level would throw an engine protection code.  Does the code clear when you disconnect the sensor?  Have you checked the wires for voltage and ground?  I think some of these use 5 volts.  Is it possible that it’s the coolant temperature sensor/circuit that is throwing the code?  

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Not sure if your rig is the same but my rig uses the Kysor Low Coolant Module that basically receives the low coolant signal and translates it to the dash warning,  Here is a flyer I downloaded.  It does show this on my wiring diagram and also check the Cummins Quickserve wiring diagram and it shows it is connected to the ECM.

I think mine is buried in the wiring behind the dash

 

 

 

Low Coolant Module KYSOR ALARMS SERVICE AND INSTALLATION.pdf

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Hey Steve. Good morning. We spoke on this matter before and and we talked about your oil pressure sending unit. Just wondering why you are suspecting the coolant level sender? Reason I ask is, usually the sender is normally open and closes when coolant is below it. Also remember that the warning buzzer is one buzzer for all the warning devices. Be sure that is the reason it's buzzing in the first place.

(Cut and paste this for you.)

A float level sensor is used to detect the coolant level inside the reservoir tank. The sensor is in a normally open position. When the fluid level in the reservoir tank is low, the magnet in the float activates the Reed Switch sending a voltage output to the customer electrical interface.

So this should tell us that if the sender is unplugged your warning buzzer should not be sounding. If it is and it definitely is the coolant sender circuit then maybe you have a wire harness crossed or one wire shorted to ground.

Best of luck. Please post what you find. Cheers.

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Post #4 explains how I arrived at this being a coolant level sensor or a short.  It was never described as anything oil related.  That came out of left field. 

There is no buzzer buzzing.  The lamp on the dash says "Warning".  

The warning is still lit when the sensor is unplugged.  Which to me supports an argument that a wire is shorted.

The coolant level sensor does not appear to use a float.  It's a sealed unit, screwed in horizontally, with 2 flat  pins inside the tank, and a 3 pin connector to the wiring harness.

I'm still searching my files for a wiring diagram...  👀

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Just from what you're saying it also sounds like a short to me as well. In order to be positive I would run a small gauge wire from the module to the sender as a test just out through the window, along the ground and cut the sender wire and attach the long wire to the sender. If your problem goes away then you know it was a short. Or if you're handy with a ohm meter you can disconnect that wire at both ends and test to see if it grounds out. Now just to add to your last comment, I have not seen a system without a warning buzzer as well. All systems I have ever repaired over the years had audio warning tied in with the light. Just mentioning this incase someone has disabled it.

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14 minutes ago, Rico K 2005 Knight said:

Just from what you're saying it also sounds like a short to me as well. In order to be positive I would run a small gauge wire from the module to the sender as a test just out through the window, along the ground and cut the sender wire and attach the long wire to the sender. If your problem goes away then you know it was a short. Or if you're handy with a ohm meter you can disconnect that wire at both ends and test to see if it grounds out. Now just to add to your last comment, I have not seen a system without a warning buzzer as well. All systems I have ever repaired over the years had audio warning tied in with the light. Just mentioning this incase someone has disabled it.

If I knew what module and its location, that would be the next step...  still looking

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23 minutes ago, Steve P said:

If I knew what module and its location, that would be the next step...  still looking

OK....First THINGS first.  Do you have PRINTS?  If NOT, then download the 2009 Knight prints.  They are in the files.  WILL BE CLOSE

NOW, in that set of drawings are TWO prints that look about the same.  One is near the top and the other near the end.  Here is the one near the end,.  

NOTICE the picture of the dash.  Find ANY one, you will have to be patient and scroll

THEN print to PDF each of the ones that look like this.  THEN match up with your dash layout.

I am ASSUMING that the WARNING light is what came one....been a while.

Look in the RIGHT Look at the PS6A plug.  The number 3 WIRE is the Warning Light.  This is a GROUND signal.  The warning Light gets power and when the #3 wire is GROUNDED...as in UH-OH....something is amiss.

NOW, you disconnect the plug and look on the HARNESS (from the rear) not the Harness going to the gauges.

Use your OHM meter.  If the #3 wire or pin is grounded (Check the pin to Ground on OHMS or Continuity....if it is GROUNDED....you will have a light.

NOW....go back to the rear.  Disconnect the wire to the sensor in the tank.  Did that CLEAR or cause the GROUND TO GO AWAY?  IF so, then the sensor is bad.

NOW>.>> What I DON'T know?  are there other sensors on that line.  OR is there a short or a NICK in the wire.  I had a DOOR OPEN light come on.  I have NO DOOR (as in the Engine Compartment) SWITCH.  My MH used a harness like the Dynasty...so the wire was in there....but not hooked up to a switch.  BUT, when it got nicked and grounded out....it was like having the switch ON or the Engine Compartment door UP.  

That is the logic.

OK....as suggested....you can build on this.  If you CUT (temporarily) the #3 wire GOING TO THE GAUGES...and the light goes away....then you know that wire is the issue...

GOOD LUCK...

Front Instrument Panel Lights and inputs.pdf

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56 minutes ago, Steve P said:

@cbr046 And what code did it throw on the diagnostic connector/port?  Or what pointed you to the PS fluid?

Pulling codes requires a shorting plug, which I still don't have.  Manual said to check levels so I started checking levels.  PS fluid wasn't even on the stick!

- bob

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21 minutes ago, cbr046 said:

Pulling codes requires a shorting plug, which I still don't have.  Manual said to check levels so I started checking levels.  PS fluid wasn't even on the stick!

- bob

Steve,

Be aware.  You must use the Shifter Key pad to check the Allison.  Doubt you have a dipstick.  Must drive it to get it hot...as in around 195 dF.  Then park and LEVEL.  Then follow instructions for used the Electronic Level Keypad.  Should have an Allison manual in your "Files" or google it.  You match the shifter style in the Allison manual and then do that.  Then other engine fluids like Oil and Coolant...

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