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Engine fan perpetually on - Printable Version

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Engine fan perpetually on - Rawze - 04-29-2021

I was contacted recently by forum member 'riklitzi', who owns an International Prostar 2010 model with a CM871.

The engine fan on his truck would not shut off no matter what anyone did.

He told me that the fan clutch had been replaced... the fan solenoid, the high pressure sensor for the A/C, and several other parts.

He also said he had it to several repair shops both OEM and non-oem to no avail. the conclusion was that it must be a bad ecm or cab controller.

It was killing his fuel mileage and driving him crazy.

He ended up delivering close to me so I told him to bring it by the house. After all, I have a prostar too. After a bit of conversation, I found out that the truck had been deleted by a fairly well known place in Illinois close to where that "diesel.Dr" idiot is located. He then remembered that it was when the delete was done is when the fan issue started ... but that they had told him it was an unrelated problem.

I pulled a copy of the program in his ECM. To say it was bad was an understatement. it had more than +17 degrees BTDC injection timing settings in all engine operating modes, it had no proper operating mode control any more, the program was for a different truck (a peterbilt) and the CPL and critical hardware like injectors, etc... were a complete mis-match. it also was set for 600-Horsepower and 2030 torque, done so in a way that would make the fuel mileage readings in the dash lie to you and tell you that you were getting way higher fuel mileage than the truck was actual doing. A typical auto-tuning-site copied garbage-can engine tune not fit to run a lawnmower, nonetheless a $40,000 commercial engine. This was clearly a bad delete program that had been copied out of another truck and shoved into his engine... just like a virus, these bad deletes spread this way like mad among our industry.

- Well, the engine fan issue was a single setting in the programming that got turned on by someone somewhere. it is a really deceptive setting for prostars and many mechanics could easily over-look it.. even a dealers$it. The settings is ...

'T_FCC_AC_Pressure_En'. ... In Insite, it is called "Air Conditioning Pressure Switch Input". - This setting switches between the J1939 (cab controller) when 'OFF" and a hard wire connection on the ecm when "ON". this was the fan issue he had.

Just thought I would share this story for others who have fan clutch issues that no one can find.