"Warning" light in dash stays on

[JohnnyDiesel]

I just bought a 2001 Executive. I noticed a red "warning" light was always on. The previous owner said it had been on for years and nobody knew why.

The owners manual eluded to a possible low fluid condition but I find everything is full. Anyone have this light on their rig?

My coach has a Cummins ISM 500 and I can't identify a troubleshooting method to zero in the cause of the light.

I checked for DTCs and there are none. I checked the wiring diagram and see that the "warning" light is triggered by the engine ECM.
The coach runs well. I drove it home 350 miles no issues.

Thanks in advance.

[JohnnyDiesel]

7 minutes ago, John Haggard said:

Code for my ISM 500 showed a bad 

For mine

Barometric pressure sensor. 

And an updated wiring harness.

$260 diagnosis and installation 

Took 20 minutes.

More power certanly 

 

Thanks John, interesting. Do you know the fault code number and the new part number by chance?

[GoSkeeterPopGo]

John, 

That is interesting information.  My 2001 HR Endeavor has the same "warning" light and on occasion it will flicker or stay on for a short period of time like when driving up a steep hill.  I thought it was also connected to fluid levels such as coolant and hydro.  One time I found the coolant a bit low, topped it off and problem solved.  However you now have me thinking it could be a bad Barometric Pressure sensor....which somehow relates to "engine power"???

At times, I feel my 330hp engine should have more power, so I am wondering if I should have this checked?  I will be passing thru Morgantown, WV in Sept on my wat to Colorado/South Dakota, so maybe I should swing in there and see if they can diagnose?

What wiring harness was upgraded/replaced?

[ko7pjim]

On my 2004 Camelot it was low coolant.  The coolant purge tank leaks a bit and needs to be replaced.

[Hancoman]

I also have 2001 executive with the 500 hp Cummins with the warning light on, had it in the shop they checked the codes found nothing. Test drove the coach no change they said they would continue to try and track down the cause but we’re not hopeful and I was already at 1000 bucks , so I said I was good. Since then have driven cross country and back with no problems. That’s my 2 cents

[Hancoman]

There were codes that they were chasing down, it’s been a year so I can’t remember what they were, I have the paper work in the coach but it is in the storage lot. It is very hot and smokey in Seattle so I am staying put for a couple days I will look ln a couple days

[Hancoman]

They did not turn the light out. Was not a Cummins shop but they did have the computer program for the codes. I eventually will have the light turned off

[JohnnyDiesel]

12 hours ago, Hancoman said:

There were codes that they were chasing down, it’s been a year so I can’t remember what they were, I have the paper work in the coach but it is in the storage lot. It is very hot and smokey in Seattle so I am staying put for a couple days I will look ln a couple days

Thanks Tom, I'll wait for your update.

John

[Chuck B 2004 Windsor]

The warning light is on for a reason.  Ignoring it will only mean a lighter wallet down the road.  Chuck B 2004 Windsor

[Chuck B 2004 Windsor]

But, what about "If So"?  Your Choice  Chuck B 2004 Windsor

[planodp]

I have a 04 Executive also with ISM 500. My warning light have been come on and off now for 2 years since I own the coach. It was doing the same for previous owner. I also don't have a code. I know on a car there are soft code and hard code. Soft code you can see it on the scanner but will not turn on the check engine light. On the other hand hard code will set the check engine light. Been looking for the issue and still haven't found it. I don't have any doubt that the coach will take me to where ever I want to go.

[vanwill52]

As someone noted, the Warning light comes on for a large number of (often not related) reasons.  In my 2000 Dynasty ISC-350, the warning light had been on for years.  I have the Silverleaf VMS-PC and its diagnostics reported "Power supply voltage invalid".  A Cummins tech could not read any code.  Several years later, the ECM shut down and coach had to be towed to replace the ECM.  It turned out the "Power supply voltage invalid" was correct.  It was referring to the internal power supply of the ECM, but Cummins could not read a code.  Once the ECM was replaced, the warning light extinguished.

I wish I could have gotten an answer from Cummins before the ECM crapped out totally.  Even though the VMS-PC picked up the code, their system does not correspond one-to-one with Cummins fault codes.

I have also seen the warning light come on momentarily under full throttle when fuel filters were just beginning to clog, and stay on permanently when the electrode in the coolant tank became corroded.  There are so many reasons for it to come on that if you can't get the code read, it does not tell you much.  It can be signaling something very serious...or not.

[Chuck B 2004 Windsor]

Hi John H, interesting.  Chuck B 2004 Windsor

[JohnnyDiesel]

Thanks for all your input. Trouble turned out to be the barometric pressure sensor.

Put in the updated version and voila, warning light is OUT!

[CLIFF918]

On 9/2/2021 at 5:28 PM, JohnnyDiesel said:

Thanks for all your input. Trouble turned out to be the barometric pressure sensor.

Put in the updated version and voila, warning light is OUT!

Johnny;

I have a similar, if not the same, problem. My low coolant light has been on since I bought the coach and previous (original) owner said it has been on for years with no issues. I don't like things that don't work and should, especially warning lights. 

The surge tank was in questionable condition, not leaking yet, so I purchased and installed a new aluminum tank and new sensor. I also replaced the two 5/16 lines that go into the top of the tank they were not in good condition at all. All other rubber lines, hoses are good.

The low coolant light is still on @#$#. 

I see where you replaced a Barometric sensor and your light went out. 

I have a 2002 Diplomat with the ISC 8.3. If this is the same where do I look for the barometric sensor??

Thanks in advance

Cliff