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Buddy
Buddy, Technician
Category: Heavy Equipment
Satisfied Customers: 730
Experience:  20 years experience. Freightliner tech for last 14 years
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A 2005 Freightliner Columbia..operating temperature

Customer Question

I recently purchased a 2005 Freightliner Columbia with a C13 ACERT (serial # XXXXX). The fan runs almost all of the time when I am driving bobtail. It even runs when the motor is below operating temperature. I took it in to a dealer and of course they said the fan is working properly. I haven't pulled a load with it yet and I am concerned that the fan will kill my fuel mileage.
Submitted: 4 years ago.
Category: Heavy Equipment
Expert:  Buddy replied 4 years ago.
HiCustomer Welcome to JA. I am Buddy, and i will try and help you out.

What is the last 6 of your truck vin#?
How long does fan stay on before it goes off?
Does check engine light come on while this occurs?


Thanks
Buddy
Customer: replied 4 years ago.

The fan stays on approx 1 to 2 minutes at a time, but it constantly kicks on. It seems like even the slightest acceleration kicks it on. Have not seen a check engine light come on. The last 6 of my VIN is P00940. Thanks for the response and let me know if there is anything else that you need.

Expert:  Buddy replied 4 years ago.
Thanks for that information.

Several things can cause this issue. If the fan solenoid looses power or a ground the fan will come on to prevent engine from overheating. The most common problems i run into is the a/c high pressure switch. If it goes open at anytime it will cause the fan to run for a specific amount of time . Usually the fan a/c timer is set at 3 minutes, but can be programmed less. This means when the switch goes open, the fan will come on and stay on for atleast 3 minutes or whatever it is programmed to after the switch closes.It does not matter if a/c is on or off for it to cause the fan to kick on. If it was a loose connection or something else, fan on time will vary each time like fan on for only couple seconds.The ecm moniters sensors also to turn the fan on. Coolant temp, oil temp, and air temp. If any of these are showing a inacurate reading, the fan will come on. I would inspect hi pressure switch and plug in at switch. Might even try jumping the wires at the switch and see if fan will stay off. I would also inspect your fan solenoid and wires at it for rubbing or corosion. I hope this helps you out . If you have anymore questions, just ask.

Thanks
Buddy
Customer: replied 4 years ago.
I had a tech jump the wires at the A/C high pressure switch and the fan still came on. I guess that eliminates the A/C causing the problem. It sounds like it might be the fan solenoid to me. Would you tell me where the fan solenoid is located and if it is an easy replacement. I have read that the solenoid is easy to replace and that it costs about $100. If so I will go try to do it myself. Thanks.
Expert:  Buddy replied 4 years ago.
Thanks for the reply. That will eliminate the a/c side causing the fan to come on.
The fan solenoid is located just below the coolant reservoir and sometimes held on by the bottom coolant reservoir mounting nut. It has 2 wires and 2 air lines going to it.I am attaching picture of it. It is callout 1 in the picture. If you have anymore questions, just ask.

Thanks
Buddy


graphic
Customer: replied 4 years ago.
Buddy, I just noticed that my odometer display shows an "ECU 128" fault code when I turn on the ignition. What does it mean and does it have something to do with my engine fan issue?
Expert:  Buddy replied 4 years ago.

ECU 128 means you have a engine fault. It is possible this can be causing your fan to run. Depends what the fault is tho.There should be some more numbers to go with this code to pinpoint the fault. Like a sid or pid and a fail number. Try using your mode/reset button to get the rest of the fault. Let me know what you come up with.

 

Thanks

Buddy

Customer: replied 4 years ago.
I don't have a mode/reset button on my dash display. When I turn the ignition key the first thing that shows on the odometer/voltmeter screen is 1_1.1 then the mileage and voltage data replace it. Yesterday it displayed ECU 128 but I don't remember seeing any other numbers. It isn't showing the ECU 128 today. Is there another way for me to receive fault codes?
Expert:  Buddy replied 4 years ago.
Thanks for the reply.
Try and see if you can blink the flash codes out. Here is instructions. They will be 2 digit codes. Let me know what all codes that show up, and which ones are on the stop engine light and which ones are the on check engine light.

Use the following procedure to retrieve the diagnostic codes if the engine is equipped with a "DIAGNOSTIC" lamp:

  1. Turn the cruise control ON/OFF switch to the OFF position.
  1. Move the SET/RESUME switch to either position. Hold that position until the "YELLOW" lamp begins to flash.

The "YELLOW" lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the diagnostic code. After a two second pause, the second sequence of flashes will identify the second digit of the diagnostic code.

Any additional diagnostic codes will follow after a pause. The additional diagnostic codes will be displayed in the same manner.
Customer: replied 4 years ago.
I came up with the following sequence of numbers by counting the number check engine light flashes: "6" then 1-2 second pause "2" then 1-2 second pause "6" then 1-2 second pause "2" then 2-3 second pause then "3" and end.
Expert:  Buddy replied 4 years ago.
Thanks for the reply

That is a flash code of 62. This for Low Coolant Level Warning. This code does not have any effect on the fan.

Thanks
Buddy

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