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Thread: why won't my ECM control my fans

  1. #1

    why won't my ECM control my fans

    I cannot get my ecm to turn my fans on. I will try and be as detailed as possible here.

    I installed Spal dual fans on my 2006 C6. The stock fan was working at the time. Simple install, connect red wire to red wire and black to black. I can get them to run manually with a casper switch. If I unplug them at the 8 pin connector up by the fuse box and jump the connection I can get them running so I know from that point down there is nothing wrong. I thought maybe the PWM went bad so installed a new one and still nothing. Once I connect the 8 pin back up I only get like one volt down at the PWM.

    I am running 2 bar OS 12605732. I've tried with the a/c and still nothing. It has to be something in the ECM, bad driver? Or maybe the green wire is cut somewhere? Anyone with any ideas? Here are my settings. Thanks




  2. #2
    Advanced Tuner
    Join Date
    Jun 2011
    Location
    Montreal, Canada
    Posts
    758
    Running a similar setup here and the settings are very similar. It must be a mechanical problem.
    2007 Corvette C6 Vert. A6
    LME LS402, Pat G custom cam, ATI 10% OD Damper
    Circle D triple disc 2600, 3.42 Diff
    YSI, 3.0 pulley, ID 1000's
    Alky Control Meth,
    ARH 1 7/8 headers,
    1009 RWHP @ 7000, 817 RWT @ 6000

  3. #3
    what I am afraid of. Guess I will trace the wire back to the ecm.

  4. #4
    still not convinced the settings are correct. I was reading this. Shouldn't my Fan State Transition Desired % vs Current State have a 1 for one fan or 2 for two fans? They are all zeros.

    if you put 90% in the 192 cell, that corresponds to state "2" from the state table. Then if you look at the output control table you see that for state 2 both output 1 & 2 are on for this state.

    here how your setup works (again). Working backwards this time.

    Look at the Ouput control table, this says that:
    State 0 = no fans
    State 1 = 1 fan
    State 2 = 2 fans

    Now look at the state table, at desired 50% it will transition from state 0 -> 1 (no fans to one fan). And at 90% it will transition from state 1 -> 2 (1 fan to 2 fans). It also says that when desired drops below 50% it will transition back from state 2 -> 1, and then when it drops below 25% it will transition from 1 -> 0.

    Now what you need to do is set up the commanded % to fall in the correct state for the number of fans you want.

    So, to switch one fan on you have a desired % like 51% (ie. greater than 50% but less than 90%). And to switch both fans on you need to have a number like 91% (ie. greater than 90%). You'll notice your stock file has numbers like this.

    Then, to switch back from 2 fans to 1 you have a number like 49% (ie. less than the 2->1 state % but higher than the 1->0 state). Then to go from 1 fan to none you have a number like 25%. Again you'll see the stock calibration uses numbers like this.

    The bottom line is you have no control of the fans below 192F (thanks GM). You will always have none, 1 or 2 fans on depending what you % you put in the 192 cell. As i said before, the only way around this at present is to run our 2bar OS which gives a range of 163-250F for the fans.

    If you want the fans to come on earlier, copy everything from the 221F cell and up, down to the 192 cell. Everything will happen 29F earlier

  5. #5
    Advanced Tuner
    Join Date
    Jun 2011
    Location
    Montreal, Canada
    Posts
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    As I said, I really don't think its your settings. Here are mine with dual spals on my 07 C6 and they work fine.



    fan settings.PNG
    2007 Corvette C6 Vert. A6
    LME LS402, Pat G custom cam, ATI 10% OD Damper
    Circle D triple disc 2600, 3.42 Diff
    YSI, 3.0 pulley, ID 1000's
    Alky Control Meth,
    ARH 1 7/8 headers,
    1009 RWHP @ 7000, 817 RWT @ 6000