Engine fan wont turn off

[davidjurss]

I have an Inline 6 adapter, I just dont have Insite yet.

[JimT]

I must apologize for one thing, I mistakenly confused your engine, an 870, with a different post about a cm2250 and pointed to the SCR can as being an issue when it doesn't exist on your truck. I updated my post, however it doesn't change any of the other information.

Bad ECM tuning can manifest itself in many ways, and that includes indirectly causing your fan issue. There could be a dozen other faults that have been suppressed in the ECM and you will never know about them, not even with Insite or other 3rd party software. As noted in other threads on this forum, the ECM on 870's is difficult to tune properly.

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As for the fan, if the problem isn't air pressure and you've eliminated every wire that can be tested with a multimeter, then the only thing left that doesn't involve throwing parts at it would be to hook up Insite and monitor the Engine Fan State. The result should help narrow down the source of the problem.

If you haven't already (I didn't see this mentioned), you can set up a free account with Cummins Quickserve and look up lots of fault diagnostics, troubleshooting info, parts and maintenance info and wiring diagrams. The troubleshooting steps usually include instructions on how to test different wires/connections for correct electrical functionality.

[davidjurss]

I just set up the Quickserve account last night. I wasnt aware of it being free, so I held off on it. Once I get home again, I'll go through it and see what I can figure out

[Lonestar10]

And people say PukeDits and all the others are such great tuners to till their in for their 3rd overhaul in 2 years due to dropped valves melted pistons their 4th turbo 3rd blown head gasket. Everyone here is trying to help you make sure your going to be successful your engine can seem to be running great with bad tuning that's internally tearing it apart like a cancer while it's trying to scream bloody murder through the ECM but it's been gagged and can't turn on the help me light.

There are 1000s of hours of experience going through every single setting in the ecms on this site between the main guys on here and they offer to take that experience and get things right for you for nothing. So maybe your tuner sat at his CPU scrolling through the 1000s of settings finding out what does what or he sat down for 5 minutes found the 10 things he needed to change just to shut down the epa garbage and called it a day. Another point is if the tunes wrong you could be giving up fuel mileage also. But you do you I guess if you don't want free help there's always the 100-150hr shops that will gladly give you 10s of thousands in dollars in advice.

[davidjurss]

(03-11-2020 )Lonestar10 Wrote:  And people say PukeDits and all the others are such great tuners to till their in for their 3rd overhaul in 2 years due to dropped valves melted pistons their 4th turbo 3rd blown head gasket. Everyone here is trying to help you make sure your going to be successful your engine can seem to be running great with bad tuning that's internally tearing it apart like a cancer while it's trying to scream bloody murder through the ECM but it's been gagged and can't turn on the help me light.

There are 1000s of hours of experience going through every single setting in the ecms on this site between the main guys on here and they offer to take that experience and get things right for you for nothing. So maybe your tuner sat at his CPU scrolling through the 1000s of settings finding out what does what or he sat down for 5 minutes found the 10 things he needed to change just to shut down the epa garbage and called it a day. Another point is if the tunes wrong you could be giving up fuel mileage also. But you do you I guess if you don't want free help there's always the 100-150hr shops that will gladly give you 10s of thousands in dollars in advice.

That's the brow beating I'm referring to.

I get it, you're adamant about proper tuning. I don't disagree with that. I just have a hard time accepting that the engine fan worked as advertised for months, then stays on, and it's all because of tuning. I won't know anything until I plug in to it and find out. It's very possible it's a grounded out wire, or a sensor I haven't looked at. I was looking for some advise on where I might check next, and instead went on this whole conversation about tuning, and how it's most likely wrong, and that maybe I shouldn't be here if I dont heed everyone's warnings about tuning. That's a bit much.

So one said a word about tuning until I said I didn't have an EGR. Now is all anyone can talk about.

[Chamberpains]

We like things 100% right around here. Very little wiggle room for the rest. We all know 1st hand how financially and personally destructive and detrimental anything else is. How and why?? because 99% of us have paid the price tag of everything else.

[tsolson]

I have a CM870, in a KWT800. Demandated before i bought it, and then checked over by reputable people on this forum. Very good information available here, and if you care about the engine at all, get it looked at. My neighbor had his deleted by a reputable guy, ran good for several month, and then nothing but trouble. Turbos, head gasket, blown motors, stop engine light flashing every morning. Worst part is, he put brand new engine in, and used the same ECM, and on his third turbo again!!! sickening

As far as engine fan, i was having a weird issue with mine last fall. Weather was slightly below freezing, but not super cold. Engine fan would come on shortly after i started the engine, and stay on. And the air pressure in the air system would drop, compressor cut in, build up, and keep cycling like that, the engine fan on all the time. I figured i must have broken air line to fan clutch. Stopped after an hour driving, shut off engine, turned on the key to listen for leaks. Nothing. No leaks anywhere. Had another driver listen as well, but no noticeable leak. Restarted the truck and it worked perfectly the rest of the day.

Next day, same temp, same issue. Fan on, air pressure cycling. Shut off truck, and restarted,no more issues. Did it for the whole week i was hauling. Still don't know what was going on. Maybe the ambient temp sensor fouled up? IDK

[davidjurss]

Yeah, I'm just gonna have to bite the bullet and get Insite and see what's commanding it

[Chamberpains]

If you have the inline adapter, Insite is all over the internet. Most of the time its pirated and posted for free. Maybe someone from here will PM you some direction on where to pickup a copy of it. That way when you get your laptop you can be ready to get on top of this problem.