Engine Coolant Level Alarm

[abyrd]

Ever since owning (6 years) my 2004 HR Endeavor with Cummins ISC 8.3 I frequently get an audible alarm with no idiot light.  I have studied the wiring schematic and I have determined that the only abnormal conditions that triggers an audible without the illumination of an idiot light is LOW  COOLANT LEVEL.  I have checked the coolant level many times and it is always in the normal range.  I have removed the sensing probe from the coolant tank and found to be clean and no signs of damage, checked with OHM meter and get infinity reading.

I contacted HR technical support requesting advice, there recommendation was to check control module (black box) that is associated with the coolant alarm circuit.  They provided me with a picture of the module but there were unable to provide me with where it was located.

The nuisance alarm doesn't bother me , because I can't hear it.  My DW tells me that it drives her crazy and it's time for me to fix it and if I could hear it I would have spent more time to find the problem. 

I think after 6 years it has finally reached to top of my honey do list.

Any help would be appreciated.

Jim

 

[hermanmullins]

Jim, I think you might find the sensor in the overflow reservoir.

Herman

[abyrd]

Herman,

I have found the sensor, can't locate the associated module (black box).

Jim

[hermanmullins]

Jim try unplugging it to see if the alarm quits. This would rule out the module.  Better have the DW listen since you appear to be among the rest of us with selective hearing.

Herman  

[wayne77590]

Just an open thought! We had a "Stop Engine" light come on in our ISB and the warning was "low coolant."  Not wanting to hurt the engine we had it towed to the Cummins place...still under warranty.  They found that a wire had come off of the pin in the engine harness. They said it would be 6 weeks before Winnebago could manufacture another engine harness for it. However, they worked on it and were able to fix the wire/pin and all was fine. 

Saying that, it may not be the sensor, module, black box, etc., and it could also be something else.  Good luck in your trouble shooting.

[abyrd]

It would be a lot easier to troubleshoot the problem is the audible would stay on.  The problem is intermittent.  We were on the road for three weeks in September and only occurred a few time and newer for an extended period.  We drove a 200 mile round trip on Christmas and the alarm was on  the majority of the time.

There are multiple inputs to the same audible device each one of them have a blocking diode to prevent a back feed to each initiating device.

After further studying of the schematic I did discover that LOW COOLANT also had an idiot light, so I am now looking at all six circuits  that initiate the same audible device. The LOW COOLANT lamp doesn't illuminate when starting the engine so I'm going to start by replacing that lamp and will them go from there if that doesn't solve the problem.

Jim

[manholt]

My sensor comes on for about 3 minutes after sitting for a 3-4 day period in cold weather.  I have also had a bad probe in overflow, disconnected it and no more noise.  got it replaced and no more noise.  On my dash, over the odometer I have a computer that lights up and said Low Coolant, my Silverleaf said nothing!

[abyrd]

If it wasn't for these gremlins we would have nothing to do during these cold wet days in the Pacific Northwest.

Jim

[abyrd]

At last the gremlin was found.

The oil pressure switch was bad.

In search for replacement switch found pricing from on line RV supplier to be a rip off (over $150).

Was unable to cross reference from numbers on failed switch or parts number referenced in owners manual.  Contacted HR tech support and they were able to identify part as VDO 360-023B.  Found part on line for $39.95, total cost $52 with tax and freight.

Really pays to shop around.

Jim

 

[wolfe10]

Jim,

Thanks for the update.  This will certainly help someone else in the future.

[manholt]

Also, a reminder to contact coach Manufacturer Tech first.

[elkhartjim]

WAIT.....stop and hold the press. A bad oil pressure switch caused the low coolant alarm or did you just think it was the alarm low coolant going off?

The only time my low coolant light and alarm came on on my old motor home a few seconds later I get a message engine shutting down. This happened directly in front of the Foretravel plant and yes, she spent her time looking at those million dollar babies while I made a roadside repair. 

[abyrd]

There are 4 conditions that trigger the audible alarm

Low Oil Pressure, over temperature, alternator and low coolant level, the low oil pressure, over temperature and alternator also have idiot lights.

Based on the fact that the oil pressure, temperature all showed normal on instruments and no idiot lights therefore I assumed that the problem must have been coolant level.

My electrical schematic show an idiot lamp for the low coolant level but mine isn't equipped with it oil pressure switch has tow post, one provides signal to idiot lamp (less than 7 psi) and the other provide signal to oil pressure gauge.

Jim

 

 

[jleamont]

Jim, glad you got it figured out. I was suspicious, usually low coolant will illuminate the STOP engine also. I am very familiar with that alarm in our HR, you can hear it from down the street

[elkhartjim]

Kind of scary the oil pressure gauge showed good oil pressure with a bad sending unit.

[abyrd]

There are two separate elements in the sending unit,  one on the audible alarm circuit, it's just a contact that is open when the oil pressure is above 7 PSI, when the pressure drops below this value the contact closes and complete the circuit to activates the audible alarm.  The circuit for the oil pressure gauge is variable resistor that is proportional to the oil pressure.

In my case only the audible alarm circuit failed,  the oil pressure gauge continued to perform normally.

Jim

[abyrd]

1 hour ago, jleamont said:

Jim, glad you got it figured out. I was suspicious, usually low coolant will illuminate the STOP engine also. I am very familiar with that alarm in our HR, you can hear it from down the street

Do you know what conditions initiate the STOP ENGINE lamp?  My manual just say stop and check fluid levels.

When I was trouble shooting the oil pressure switch I initiated the STOP ENGINE, there must be a small time delay before the STOP ENGINE annunciator window illuminates.

I have spent my entire career in hydro electric power plants, I am no stranger to nuisance alarms.  It sure is difficult to identify problems that are intermittent.

Jim

[hermanmullins]

One of the big problem is the Alarm sound the same for Low Coolant, Low Oil, Low air Pressure and even the Jacks. If idiot light don't come on some times hard to know one from the other.

Herman  

[abyrd]

13 minutes ago, hermanmullins said:

One of the big problem is the Alarm sound the same for Low Coolant, Low Oil, Low air Pressure and even the Jacks. If idiot light don't come on some times hard to know one from the other.

Herman  

My low air pressure has a dedicated audible alarm, it will wakeup the dead.  It no way that you can ignore it.

JIm

[jleamont]

Jim, you must have the same low air alarm we have . Ours has one alarm above the brake pedal that does them all. On our coach the following turn the stop engine light on;

low coolant

low oil pressure 

over engine temperature (coolant)

i might be missing one more.