2012 Kenworth T660 Cummins - Radiator Fan RUNS ALL THE TIME!

sub'd. I had the same truck and the same thing happen during the winter. It just stopped one day on it's own, but I'd be curious to find out what the real cause is if you find it.

 

Holly crap. $5,000!
Are you in familiar with ohmmeter? What the clutch style is on your truck electrical or air actuation?

 

At the time I was just a rookie company driver so i didn't give it too much thought. I'm a rookie owner operator now so I'll take some guesses.

You obviously had a parts changer at KW rape you. The fan is usually controlled by an electric over air solenoid at least on these old Caterpillars.

In order to be activated something needs to send/disconnect power to the solenoid directly or the ECM pin dedicated to the fan solenoid depending on how its set up.

I would think the primary things that would do this would be the

AC high pressure switch
Temp sensor trips engine fan parameters (usually 210* on that motor IIRC)

On mine I recall the engine coolant temperature sensor would be pegged all the way below the bottom temperature range like the temperature gauge was not getting a reading although at the time I just assumed it was really cold because I was running between Spokane and Chicago the middle of winter on a dedicated route type deal when I had the issue. It would never warm up because the fan would never turn off from cold start and it was sub Zero and I didn't have a winter front.

Another possibility though stemming from that is perhaps theirs an issue with the wiring harness leading up to the coolant temperature sensor that's causing sensor issues although I would think that would throw a CEL, but you never know.

If the ECM can't get a temperature sensor reading it would stand to logic it would leave the fan on constant to avoid an overheat.

 

Well Start from the basics need to see if fan has mechanical problem with fan or something is keeping it on. if you bypass the solenoid with an air fitting you will be able to tell this really easy as the fan should disengage. Also certain times when you cycle ign fan should go off. Once you have isolated the problem then it's easier to diagnose. some things that make these fan stay on they have obviosly replace everything unless you have a fan switch on the dash the only other thing left is to check the wiring between fan solenoid and ecm and if that is all good then try to see if you could find another ecm just to test if i have seen some cummins that have problem with ecm and they never shut off the fan. just start first thing make sure it's fan problem or if something is asking for it let me know what you find out and ill help you from there

 

Sounds like they are all missing something simple to me, have seen this before when it has been a parameter setting incorrectly set. might try comparing print outs of features and parameters with another truck.

 

Just use Insite to see what exactly is requesting the fan be on. It'll tell you if it's the ac, coolant, or intake air temp.

And let's not forget the fuel temp. When it's cold out and your start the truck, the ecm will call for the fan to put a load on the engine to help it warm up quicker to get the fuEl temp in range.

 

I've got a 2013 kenworth t660, mine does the same. Turns out you have options on fans when ordering, I have a 2 speed fan and I'll bet you have one too. My fan is designed to stay on from 500 rpms and up, when the truck hits the clutch engagement temperature the clutch goes to high speed. So it's normal, and it's made like that for local trucks to help keep the truck cool in stop and go traffic. But sucks down fuel mileage if you're linehaul like me. Its a 1400 dollar fix, they have to replace your water pump and fan and clutch. I said to hell witrh it and im just dealing