2008 VNL780 adding manual fan switch

Discussion in 'Volvo Forum' started by KB3MMX, Apr 16, 2015.

  1. Pablo-UA

    Pablo-UA Road Train Member

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    Ben, as I remember, fan clutch is controlled by engine ECU, not VECU.

    But EECU controlls it via negative wire. Positive wire of all solenoids is powererd from cabin PDM, but if u pull out fuse all solenoids including jakes, EPG wont working.

    A/C actuates fan, but via J1939 request from Climate Unit.

    Not sure about VECU, may be it has auxilarry inputs U can program to send fan actuation request by J1939..... With cummins things are much easier.
     
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  3. benrab

    benrab Medium Load Member

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    Hi Pablo,
    Your right the EECU is controling the fan solonoid by the ground for water temp,engine oil temp,intake air temp but the VECU is sending a message throught J-1939 (Can) to the EECU for A/C fan request and Manual fan request when installed.
    I did more than one time in the past and it work.
    Also if it can help i keep in my note at the shop the correct Volvo part number for the special terminal + 2 inch of wire to install the PA 19 (green connector) of the VECU.
    If my memory is Ok that terminal is ( JAE Japanees Aviation)
    Ben
     
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  4. benrab

    benrab Medium Load Member

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    Pablo,
    I found the P/N for the Volvo terminal 3948725 to install at the location PA 19 of the big green connector on the VECU, also no parameter need to be change to run the manual fan option, but i remember there is a ajustable delay for the fan operation and normally is factory set at 30 second that means when you turn the fan clutch OFF it continue to say engage for the next 30 second and then stop.
    Let me know if someone will do it.
    Ben
     
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  5. Pablo-UA

    Pablo-UA Road Train Member

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    It is unused pin, the problem that u need female terminal to fit additional wire. I used to get terminals on JYs.

    Other idea - use BBM.
     
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  6. benrab

    benrab Medium Load Member

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    The PA19 cavity is not used,the terminal (female) comes with a 2 inches of wire already crimped to the terminal.
    Today at the shop i will take the terminal in my hands to double check the P/N and i will let you know.
    About the BBM yes it can works too but not all trucks are equipped with.
    Ben
     
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  7. benrab

    benrab Medium Load Member

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    The Volvo P/N 3948725 is the correct terminal to install in the VECU connector, still available at Volvo warehouse.
    Ben
     
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  8. Pablo-UA

    Pablo-UA Road Train Member

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    And u need Dev2tool to actuate fan override switch
     
  9. KB3MMX

    KB3MMX Road Train Member

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    Wow, you guys are a little over my head, I'm trying to learn though.
    So, I get this Volvo P/N 3948725 for a computer pin and wire and it gets installed into a blank spot "PA19" on the engine computer plug?
    Or is "VECU" inside the truck?

    What is dev2tool and what electrical signal is needed to be sent to the pin once installed? + 12v or Ground ?

    Also, what is the BBM and the thought on how it might work to turn on the fan?

    Thanks guys for all your help!!
     
    Last edited: Apr 21, 2015
  10. Pablo-UA

    Pablo-UA Road Train Member

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    VECU - vehicle control unit, cab controller.

    Dev too tool - is the software tool for changing Truck parameters.
     
  11. KB3MMX

    KB3MMX Road Train Member

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    Thank you Pablo and Benrab!
    Ok, I called and ordered the pin w/wire today, was about $14 at the Volvo dealer.
    Where can I locate the VECU in the truck cab and do I ground out the pin on pa19 to activate?

    Thanks!!
     
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