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Discussion Starter #1
Hi, new to forum.


My class A motor home with 260 ISB Cummins has been sitting for 28


days since last trip. I started it up and the service engine light came on along with alarm and blinking red light that shut the engine with in 30 seconds. I checked the oil,good,checked water antifreeze,good.checked oil pressure,good. I bought some CRC fuel conditioner and added that following bottle directions to my full 70 gal. tank. That was this past thursday. I tried starting it 4 times each day since. Still no luck. It starts up,then shuts off. Anybody have any idea's. Thanks for any advice.
 

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While its running do all the guages work?


Like if the oil pressure sensor is bad, it will tell the truck to shut down, even though it really has oil pressure. Same with the coolant switch, if the switch went bad your still stuck.


I'm afraid you will have to have a reader to get the info to go any farther. Because Your cab guages may read correct, but the engien may use a seperate sensor for the ECM.


Example, International uses the same sensor to run it's dash gauges that the ECM uses for inputs, If the gauge don't read anything, real easy place to start is sensor. Freightliner on the other hand uses a seperate sensor, so the gauge on the dash may work, but the sensor for the ECM may be bad, and you won't know without a code reader. I know kinda silly, but hey it's a Freightliner.


If you don't want to pay a tech to come look at it, I would recomend replacing the oil pressure sender, and the Coolant level sensor. You may still end up getting a tech out there, but those would be the two most common.


Actually you can unplug the oil sensor and the engine should still idle, So you can try that.Edited by: Traveler
 

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Traveler,


Thanks for the reply. Yes,all gauges work. My oil pressure is at 75psi idling. Are you saying,take oil sensor wire off and engine should still idle,and that would indicate that oil sensor is good. How about temp. wire,if I can find it.
 

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Okay I read your original post a little closer, Is the engine dying? or just the engine light?


I was under the assumption it was dying after 30 seconds, I see that may not be the case. If it was dying you can unhook the Oil pressure sensor and it will keep running. The low coolant sensor in the overflow tank will kill it also, not the high temp switch as stupid as that sounds. If it is dying the oil sensor is ahead of the starter on the side of the engine block. If the engine was dying, you unplug the sensor, if it continues to run, the sensor was bad. the check engine light will stay on with the sensor unplugged, just trying to get it moving.


If the engine is not dying, it could be many things, and you will need a code reader to be sure. Those engines have oil pressure, coolant, Engine position, coolant temp, throttle postion, and many other sensors that will turn the light on, but not affect the drivablility. They have codes for telling the condition of the electrical circuits. It could be a low voltage fault if the batteries were low while you were cranking.


If the thing still drives, drive to a cummins dealer and have them just plug in and tell you what the ECM thinks is wrong, if they won't tell you how to fix it, just post what they said the code was, and I can tell you what it is.
 

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Discussion Starter #5
Traveler,


Engine shuts off 30 seconds after red blinking engine lite appears.


When engine starts,service engine lite comes on. Runs 1 min. then


red blinking lite comes on. Then in 30 sec. engine shuts off. It will


start right back up. Batteries are stong. Diesel gen-set starts and


runs just fine. I let it run for 1 hour. I called my Cummins mech. He


will be out of town untill Monday.
 

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I would look for the oil pressure sensor then and unplug it. It should be in the side of the block, towards the front of the motor. Probably frame rail level. If you can get to it, pull the plug and retry it. I can't remember for sure on the ISB, if you don't see it there, look around the oil filter housing.


The coolant sensor should be in the top of the radiator, or overflow bottle if it has one. Just try and unplug it as well.


If you can find the coolant temp sensor you can try and unplug that as well. It should be on top of the motor, towards the front, Turbo side. I think its two wires. Very near the thermostat housing or water outlet.


When you unplug a sensor the ECM goes to a default value, it may on idle, or give like 1,800 rpm, but it will run. the ECM thinks it has a bad wire, before it assumes the engine has other problems.


Each one of those items will cause a fault code, but will go out when plugged back in.
 

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Discussion Starter #7
Traveler,


Thanks a million for your help. I pulled a 4 wire connection that went to a 2 gal. black tank,that fed water to the radiator and to a clear bottle that you would ad antifreeze to. That wire cleared the fault that was shutting the engine off. Now the check engine lite is on,but the engine runs.
 

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That's the overflow tank, and the bad sensor would be the low coolant level sensor.


Glad you got it going.
 

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Discussion Starter #9
Traveler,that bad sensor was a good sensor. 2 gal. overflow tank was emty. Plastic type sight bulb in tank was cracked and allowed coolant to spray out untill empty. So the sensor did it's job. Thanks to you,I found the problem Edited by: Smokyjoe444
 
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