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SW900 SW 900 LCD P09 zero start What does it mean?

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    SW900 SW 900 LCD P09 zero start What does it mean?


    New ebike build and I'm having an issue with PAS not working. Throttle works in both P10 set to 2 or 3 but PAS does not do anything with PAS set to 0 or 2. I have the manual the LCD SW900, I have the "manual"; I believe I have everything installed, connected and set properly but PAS does nothing no matter what I do. Deciphering the LCD "manual" is a challenge, but here's the PAS settings I have set...

    P05 PAS grades, set to 0; note I have 3 settings available 0,1,2. The 2 setting is not mentioned anywhere but it appears to allow another option for PAS grade, 2=9 PAS grades. Maybe it's a new version of firmware, I tested and that's what it does

    P07 Speed measuring magnet, set to 50, I'm not really sure what this does or if it affects PAS so I set it to 50 figuring right in the middle is a good choice

    P08 Speed limit, set to 100; note manual says 0-50 but mine has 0-100, again maybe new version or firmware

    P09 Zero start; set to 0; again, I'm not sure what a "Zero start" is, can somebody clarify?

    P11 PAS sensitivity, set to 12; I'm not really sure what this does or how it affects PAS so I set it to 12 figuring right in the middle is a good choice, can somebody clarify?

    P12 PAS start strength; set to 3, I'm not really sure what this does or how it affects PAS so I set it to 3 figuring right in the middle is a good choice, can somebody clarify?

    P13 PAS magnet type, set to 8, 5, 8 and 12 are the available options. I think this is the number of magnets on the PAS, can somebody clarify?

    and, is there a ways to reset the LCD to the default factory settings? I've tried so many different combinations maybe this will help!

    In advance I apologize for my ignorance and thanks to any and all who can provide some guidance!


    RC, I have the 36V 500W geared 26" rear wheel kit from Ebikeling.
    I am gradually gaining an understanding of the SW900 parameters & overall system behavior.
    I'm surprised no one has replied... As for why your PAS may not be working, I have 4 ideas.
    1) I had to partly disassemble my crank, so that I could install the PAS system, comprised of a disk containing 8 magnets & a sensor.
    The small plastic wheel embedded with 8 magnets spins as the crank turns (pedaling) & the sensor is snugged into a fixed position at the crank.
    Simply, the magnets moving past the sensor tells the controller that you are pedaling.
    My disk containing magnets had an arrow indicating the direction it needs to spin while pedaling. So, it has an inside & outside.
    I was puzzled & skeptical at the time that the magnetic field orientation of the disk was important, thought it should work fine either way, but I followed directions.
    That spin-direction-instruction suggests that it may be critical that the magnets are oriented a certain way, so the magnetic field is properly sensed when passing the sensors.
    2) My sensor can be mounted correctly (sensor located outward towards the magnetic disk), or incorrectly with sensor oriented away from the magnetic disk.
    I seem to recall watching a kit-assembly video where the builder misoriented the sensor. That sensor should be locked into place on the crank with an inner nut.
    3) The important spacing between the rotating magnetic disk & the sensor is just like mounting the magnet & magnet sensor on your traditional bike computer.
    If the spacing is too far, the sensor doesn't notice the magnet, no speed is calculated & displayed at the computer.
    4) The sensor harness, 3-wire I think, must be correctly connected to the appropriate mating connector at the controller.
    SO, is the sensor orientation right, fixed in position? Is the spinning magnetic disk oriented per directions? Is the magnet to magnet-sensor spacing narrow enough? Connection?
    RC: Please let me know your current status of PAS & the actual solution you determined to fix you PAS.
    I'll check back, hope to both learn from, & contribute to, this excellent forum.


      BTW: zero-start (P9=0) I believe corresponds to how quickly pedal-assist kicks in. Zero-start chooses a more immediate assist, whereas non-zero-start (P9=1) applies a 1-2 second delay before assist kicks in.


        Hi can anyone post default settings for sw900 display please as i have changed the settings and now going really slow I have 250w motor and 36v battery thanks