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Setup and troubleshooting BBSxx speed sensor

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    Setup and troubleshooting BBSxx speed sensor

    When setting up the speed sensor its important to make sure that the red led light is on when the motor powers up. This needs to be approximately 2mm (1/8 inch) from the magnet. Refer to arrow below (Photo 4) NOTE: If the speed sensor is not close enough then you will get an error code 21 or 15H on the display If the red light is not coming on and off when the spoke magnet is going past the sensor then there could be a couple of reasons why.
    1. The sensor hasn't been plugged in far enough and tightened fully up. Check connection and tighten.
    2. If the cable been damaged during riding then the cable will need to be repaired.
    3. Sensor is not close enough to the magnet. (needs to be less than 2mm) Note: Sometimes the motor will shut down without giving any error message due to magnet placement being too far from the sensor. Test that it is not a distance issue by physically holding the magnet/sensor in your hands and manually swiping the magnet across it while the bike is powered on, check to see if the LED flashes.
    4. If the sensor has been checked and its been set up correctly then the other thing is the sensor is faulty. New sensors can be purchased here:
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    The speed sensor is attached to this cable in the photo above (Refer red arrow). Its one of 4 cables that come from the controller. This motor is a BBS02 but the BBSHD is the same. This applies to version 2 controllers.
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    I always use cable ties to keep the sensor in position.
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    Its important to keep the cable away from the rear wheel.I always come from the bottom and then over the swing arm and keep the cable tight with cable ties.
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    If you are using 750c display and see error 15H (this is same as error 21), you likely have the magnet too far away from the sensor which will trigger this error, or the sensor wire is not fully plugged into the sensor, or not screwed in fully, or the sensor itself is defective. The DCP-14, DPC-18 and other color displays speedo error code is error 21. If the speed sensor is faulty the display may bring up the error code. On older controllers the display may be able to be programmed to not shut down. If you go into settings and select Auto off to never to shut down. Not all displays are guaranteed to have this function and not all controller firmware is guaranteed to support it, but you may want to give it a try. This video can be of help at 35 seconds it shows the Auto off function:
    Note: Likely if you are reading this page, the magnet just needs repositioning. However, assuming it is set up correctly, there are two other possibilities.
    • The speedo itself has gone bad and needs replaced
    • The controller is damaged and needs replaced
    Sometimes the speedo sensor can get tangled up in spokes during use if it falls off and pull the wires out of the controller, which would necessitate replacing the controller. If so, the controller is available in the parts section. As to the speedo sensor itself this is less likely to fail but not altogether impossible given the positioning puts it fairly exposed to debris, physical impact and water. Replacement speedo sensors can be bought here.
    Edge cases In some rare situations like fatbikes, you may not be able to get the mount/magnet close enough. There are some examples of how to fix:
    • Attach small 'rare earth magnet' to the existing magnet to extend its range, these can be found on ebay etc and are quite powerful
    • Shim the chainstay before attaching the sensor mount. This involves placing something between the mount and the chainstay, affixing with something like doublesided tape, then running zipties over top to reinforce. For a short video explaining this see below
    Last edited by Rodney64; 12-20-2017, 01:06 AM.

    Testing the speed sensor:

    Now you can test the speed sensor with a basic multimeter, just need to set it to Vdc mode (if you have a range select 0-20v). If you meter probes are too thick you will need to put little metal wires in the holes (can be needles, a leg of a resistor ...etc). See picture below:

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    This next drawing shows you which pin does what and what voltage you should get (don't forget to power the system before testing)

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    If you do not have the same voltage reading, then it's either that you are not probing correctly or that the controller is not supplying the right voltage.
    IF you have the right voltage that would likely point toward a bad sensor (or magnet issue)

    The next step is to test if the controller can receive a signal from the speedo sensor, just need to put a pin in the ground and another one in the signal and short them out at a steady pulse, see next video:

    If you get a speed reading doing this than it likely means the sensor is bad or that the magnet is on the wrong side or not facing the crosshair! If you don't have a speed reading then it's likely the controller or the display.