Issues with hall effect thumb throttle not going to 0v.

I use this pretty generic hall effect thumb throttle with my BBS02. Right now my BBS02 keep reporting error 04 anytime the throttle is plugged in (unable to zero the throttle).

I ripped it apart to the PCB inside and checked all the wiring and it looks fine. I get +5v on the red +5v wire, but the blue signal wire seems to be stuck at +2.3v as if the sensor was always at 0 gauss. When I move the throttle lever the voltage on the signal wire doesn't fluctuate, but if I take a strong neodymium magnet and put it next to the hall effect sensor it will drop to 0v and up to +5v depending on the polarity of the magnet.

The magnet in the throttle lever still seems to be polarized, just the sensor isn't detecting the polarity as if it isn't sensitive enough. Is it possible the hall effect sensor itself is bad even if it works with a strong neodymium magnet?

I attached a picture of the hall effect PCB schematic that I sketched out. I have no idea what the 1.2k resistor is doing in this case but it is there on the PCB.

is there a steel plate around the Hall Sensor that fell out? The steel plate's function is to guide the magnetic flux thru the sensor.

Sometimes the magnets come unglued and move inside the throttle body. Sometimes two magnets are used, and if one comes off it does what you see at either high or low throttle range, depending on which one fell off. (but it would still work for the other half of the range)

I dont' see any attached image; you may need to go to the attachments tab below the text box and verify that it actually attached correctly.

If it's a link to an external site, those dont' always show up for eveyrone. (attachments do).

I do see the circuit diagram picture, and it was visible to me when I first posted.

Of course, everyone's results may vary.

I have had many a thumb throttle go bad due to a failed hall sensor. The real one is the Honeywell SS49E. (for most, but not all throttles.) The generic one is simply known as a 49E hall sensor. https://www.mouser.com/ProductDetail/Honeywell/SS49E?qs=/fq2y7sSKcJBD3o5K2Vcgg==
The link might fit you need.

I seem to go through a thumb throttle at least once a year and always have a working spare on the shelf. It might have to do with how I release the throttle and is snaps back to 0v. If the magnet pounds into the sensor, it could break a wire. They are small.

AW is correct about the magnates sometimes rotating in their mountings and suddenly the throttle doesn't work right. Cheap throttle manufactures don't really cement them into position very well.

Do you have any pictures of your throttle?

If you are sending 5v+ to the red wire, grounding the black wire and getting a voltage from the return wire (the third throttle wire) then you have a bad Hall or one or both of your magnates flipped.

Are you sure there is a 1.2K resistor from +5V to ground? What purpose could that possibly serve? Other than to waste 4 milliamps continously?

If the throttle's magnet is passing over the sensor (SS49E) within say a couple mm. I would have to go with a bad sensor. A good SS49E will not put out 0 vdc or 5vdc no matter what the gauss. Typically around 1vdc to 4 vdc as there will always be some loss in the electronics.

Best guess I have on the on the resistor is that it will drop the input voltage .12 vdc, thereby dropping the output on the sense line. Perhaps to stay under the controllers "shorted sensor" voltage lockout setting... or error 5 throttle abnormality....?



Regards,
T.C.

When installed and the bike is turned on, his kind of throttle's return wire typically reads .8v in the stop position to 4.7v in the WOT position. at 1v the motor starts moving. At 5v, some controllers read an over-voltage and cuts the power to the motor.