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Open Roads Forum  >  Class A Motorhomes

 > Stranded in NY - Cummins ISB2 - Limp Mode?

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ktanderson

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Posted: 04/06/12 11:01pm Link  |  Print  |  Notify Moderator

Lost coolant due to a broken hose clamp on a 2007 Pathfinder Cummins ISB2 with Freightliner chassis. Replaced clamp and coolant. Engine runs fine with no overheating, but computer says 'low coolant' and appears to be in 'limp mode' as it won't go over 30 MPH.

Do I need to purge cooling system and if so how?

Bad sensor?

How can I restart the computer?

Currently stuck in Batavia, NY.

rvrepairnut

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Posted: 04/06/12 11:05pm Link  |  Print  |  Notify Moderator

ktanderson wrote:

Lost coolant due to a broken hose clamp on a 2007 Pathfinder Cummins ISB2 with Freightliner chassis. Replaced clamp and coolant. Engine runs fine with no overheating, but computer says 'low coolant' and appears to be in 'limp mode' as it won't go over 30 MPH.

Do I need to purge cooling system and if so how?

Bad sensor?

How can I restart the computer?

Currently stuck in Batavia, NY.

try disconnecting the two starting batterys.leave the cables off for
60 seconds. go and turn key on and try starting the unit with the batterys disconnected.Then rehook and run unit and see if this clears the ECM for you

Jackthewonderdog

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Posted: 04/06/12 11:14pm Link  |  Print  |  Notify Moderator

I'm surprised it even runs in limp mode. I would be looking for Emergency road service to get me to a shop before you damage the engine.

ktanderson

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Posted: 04/06/12 11:25pm Link  |  Print  |  Notify Moderator

We shut down the motor before it even got close to overheating. Fixed the clamp on the hose, re-filled fluids to proper level and engine will run great. Problem is it's still in this limp mode, despite engine operating at correct temperature. Baffled.

BobsYourUncle

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Posted: 04/07/12 12:15am Link  |  Print  |  Notify Moderator

This might be a long shot, but I wonder if disconnecting the battery for a few minutes would reset the computer?


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Posted: 04/07/12 02:17am Link  |  Print  |  Notify Moderator

No doubt you still have one or more air pockets in your system. Here's how to "burp" the system. You've already refilled the radiator...(I'm assuming you've refilled with the proper coolant)...
1. Let the engine cool and recheck fluid level. Top off.
2. Remove the radiator cap and run the engine to operating temperature.
CAUTION: Do NOT let it OVERHEAT!!!
3. You should hear the radiator burp as the water pump forces the air out.
4. Refill the radiator and coolant reservoir to the top.
5. If this doesn't correct the problem, you may have another air pocket so let the engine cool down completely and repeat the process.

I would also call Cummins for advice......replacing an engine is very expensive....Dennis


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dons2346

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Posted: 04/07/12 10:19am Link  |  Print  |  Notify Moderator

Have tried the Cummins tech line?





ktanderson

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Posted: 04/07/12 10:57am Link  |  Print  |  Notify Moderator

Found the problem! It's possible it was an air bubble. After engine cooled last night, we re-filled with more anti-freeze and water. The thing took nine gallons, but runs perfectly and all error codes went off!

Bravo folks. Thanks for the help!

mpfireman

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Posted: 04/07/12 09:21am Link  |  Print  |  Notify Moderator

Do the battery thing first. If a no go, contact a dealer for a re flash to the EMC.


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randallb

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Posted: 04/07/12 07:00am Link  |  Print  |  Notify Moderator

First, an air pocket in the block will not give you a low coolant light, the sensor is in the coolant reservoir. Second, the thermostat has a bleed valve in it to allow all air to transfer from the block to the coolant reservoir. You may have overheated the engine and not had the temp gauge show it. Air around the temp sensor will not transmit heat to the sensor. Get the vehicle to a Cummins shop and have them check and/or clear the fault codes. There may have been an issue created by a possible overheat and/or coolant in a connector. I am kind of leaning towards a flooded connector but I am not there to look at the RV directly.
Randy

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