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Thread: 2 Speed Fan Programming

  1. #1
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    2 Speed Fan Programming

    Using an E40 ECU from a 2006 GTO and i have 2 fan outputs fused/relayed/wired. typical dual fan setup is 1 output coming on, then the other at a higher temp. but i am using a 2 speed taurus fan, and need a single output on at a given time. output 1 operating the low speed function, output 2 operating the high speed. first off... first time i am looking at this ECU and its not the same as what i am used to looking at with my truck ECU.


    Under the Relay Controls... for "Fan Output Control vs Current State," a value of "0" is off, a value of "1" is on. so i believe i can use this to control the 2 speed fan as needed. but i am not sure what the state it is referencing is.


    under "Fan State Transition Desired % vs Current State." what am i looking at here? what does it mean by both fan state and current state?

  2. #2
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    https://forum.hptuners.com/showthrea...ll=1#post52393

    And all you have to do to have only one fan output pin active at a time is put a '0' in the box where you want the fan pin OFF. A '1' in the box means when those conditions are met in the other tables the output will be ON.

    States 3 thru 7 are never used, since you have only two pins that can never be anything other than either on (1) or off (0). The stock settings keep 1s in the unused boxes because there's no reason not to, those other states aren't used.

  3. #3
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    like so?



    i am still unclear what the "state" is that is being referenced, and the % as well.

  4. #4
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    State is 0 or 1, OFF or ON.

    State Transition is 0>1 (fan 1 from OFF to ON), 1>2 (fan 2 from OFF to ON), 2>1 (fan 2 from ON to OFF), 1>0 (fan 1 from ON to OFF). You are only using two States and two output pins so the other rows/columns in those two tables will never be used, they can be ignored.

    Look at your #18040 table. You need a '12' or more to turn fan 1 on, and a '10' or less to turn it off. '24' or more turns fan 2 on, '20' or less turns it off. Those numbers come from the cells in the Desired% vs ECT/AC tables. They are not actual fan speed percent like with a variable speed fan where what you command is what you get, they are just used to look up in the other tables whether a pin should be ON or OFF.