Brand new Bafang Ulta / G510.1000 / m620 speedsensor/controller problem (need wireing diagram))

[motorm3ssie]

Hey,

i just finished my latest project today (at least i thought so) and was about for a test ride. I did build a completely new fully mtb with a Bafang Ultra. To provide the power i did build a 60a 14s4p Sony VTC6 pack. I love the bike already

But the motor kit has a problem with the speed sensor or most probably the controller. The display is not showing any speed while driving and after a while error code 21 pops up.

There was no wireing diagram included, but i think i got it right as the connectors are all different.

The connector for the speed sensor has 3 wires, all colored white. I did measure the voltage, but its not consistant and very low. Wire 1 at the beginning has had 0,8 volts. Wire 3 seems to be the ground. After turning the motor on and off i suddenly had 1.3 volts at wire 1. And now for the last few mesurings i only had 0.46 volts at wire 1. One time i did pick up a short spike of 4.9 volts while mesuring during the boot of the display.

My guess is a faulty controller and i think the sensor probably needs 5v. But thats just my guess and i dont want to push 5v into the sensor to test it and maybe destroy it because my guess was wrong.

So my questions are:

1. Does anyone of you know how much voltage should be supplied by wire 1 or 2 or 3 from the connector to the speed sensor?
2. How to fake a speed sensor signal to test the controller? An how to test the speed sensor?

 

[motorm3ssie]

I couldnt wait and took the risk of testing it. Sensor seems ok at 5 volts. But while testing the matching connector on the controller side speed did not work. But i noticed the battery voltage level on the disply getting malfunction while testing, so i measured the other connector wich i left unused because i thought it would be for the battery info and realised that this is the right connector for speed sensor. BUT ITS THE WRONG CONNECTOR AND NOT MATCHING TO THE SENSOR. So i dont gave a frock about warranty and opened the motor to see whats going on



Point 1 is where the matching connector from my speed sensor goes to, but its obviously for battery info
Point 2 is where my speed sensor should go to, but the connector is not matching

Did any one of you had the same problem with a non matching connector? While surfing and looking for a new speed sensor i noticed that the yamaha speed sensor looks almost like the bafang one, only the connector is different and looks exactly like i need it. So i think they most probably put the wrong connector on my speed sensor, because it has a 4 pin connector but only needs 3 pins.

I dont want to cut cables on my brand new motor

 

[motorm3ssie]

I had contact to another Bafang Ultra owner and he confirmed that his speed sensor connector has 3 pins. So they just put the wrong connector on my speed sensor. I did just cut the cables and connected it myself.

For anyone who has the same problem: There were 4 cables comming out of the speed sensor. Red, black, blue and yellow. Red and black are obviously power supply. Blue and yellow are signal wires, for me they were exactly the same so i just left one of them blanc.


Bike is running. Case closed

 

[Drakesnake]

Bought my Ultra G510 1000w in January 2020. Didn't assemble til last month.
I'm having the same issue with the speed sensor and an error 21. Everything else seems to work.
Checking the speed sensor connection at the motor, I have 4 pin connectors but only 3 wires used going into the motor (1 pin plugged/not used). The speed sensor has 4 wires (blk, red, yel, blu). Interesting that blk wire here isn't connected ??? I have another 3 wire connector (unused) also coming from motor.
I unhooked speed sensor and tested the 4 conductor speed sensor connector from motor and only get about 400mv across a few of these pins. I believe it should have 4-5vdc. Not sure however, because I haven't found any wiring schematics anywhere!! I know BBSHD uses 5vdc for 3 wire sensor (+, -, signal) - should be similar??
Are you saying that the speed sensor needs to be hooked to the unused 3 wire connector at the motor? If so, what is the correct wire designations?? All the wires are white here, so not sure which wire is +,- or signal, from motor ?? I did measure 5v+ on 2 of the 3 white wires from motor. So, one these is 5v power, another gnd, and other is signal - not sure which one is signal?? Also, I'd need a 3 wire connector to do this best. Thanks for any help!

 

[Drakesnake]

I've confirmed that the 3 pin connector from motor is in fact the speed sensor input. Bafang has wired some of the speed sensor cables with 4 conductor connectors. This means that the sensor cable doesn't fit the 3 pin connector at the motor. It fits, what I think is, battery sensing input. I found another sensor and cable from California Ebike ( very good responsive tech support with this company BTW) and its wired correctly with the 3 pin connector. The cable from bafang likely is ok, but 4 pin connector needs to be removed and wired properly with 3 pin. Not yet sure of correct pin designations??
Problem solved!

 

[tomjasz]

The end results?

Thanks!