BBS01B stopped working

[JWBrown]

My BBS01B (250 W 36V #1710090097) stopped working.
-Battery is charged and reads 41 volts at connectors between battery and mid drive unit. Voltage checked while power leads from battery were connected to motor unit.
-C965 display is blank-not working.
-Unplugged, inspected and carefully replugged all external connections
-No voltage at 7-pin cable exiting motor unit leading to display and brakes
-On day the motor stopped working, I was riding normally and lost power and display. I noticed some moisture clouding beneath display glass that same morning which quickly dissipated. Bike never ridden or stored in rain and never sprayed down with a hose, but has been stored for a few months in a slightly damp shed in dry Southern California.
-Have not split motor unit to check connections there. Motor has less than 100 hours and has never been opened for service
-I bought and installed the kit new from China - no other owner.

Please suggest troubleshooting steps.

 

[harryS]

-No voltage at 7-pin cable exiting motor unit leading to display and brakes

Sure it's not an 8 pin cable? I thought the BBS01, BBS02, and BBSHD had similar wiring. You'll get the battery power between pins 1 and 8 on that connector.

If you leave that connected, you should see battery power again on the 5 pin display connector.

People have run their BBS drives with the display bypassed. I recall doing it once on my own BBS02. Jumper PL and P+ on the 5 pin connector. PAS will work, and so will throttle. It's discussed in this thread.

BBSHD without display - Electricbike.com Ebike Forum

Is there any way of running a BBSHD without any display? Some way to set the HD to remember settings then remove the display? Maybe some type of jumper

electricbike.com

If you're not seeing battery power on the P+ pin, there's your mystery. I wouldn't know where it's broken. That should be a direct connection between the red battery input.

 

[JWBrown]

Thank you harryS for the wiring schematics. That is very helpful for this diagnosis. And yes, of course you are correct. It is an 8-pin connector.
I will once again test everything based on this additional information. If I don't get any voltage, I plan to open the motor to test power on either side of the controller.
Separately, is it possible to test whether the display is functioning by giving it power? Can you tell me what the following are: P+, PL RxD and TxD?

One more piece of information. I got help over on Endless Sphere a couple of years ago when I accidentally pinched the wires to the speed sensor while installing a kickstand. It must have shorted the hall sensor circuit within the controller because I eventually had to install a simple reed sensor to get the speedo back up and running. Could this have led to some eventual failure within the controller?

 

[harryS]

The display should power up without a controller. I've never done it on a my Bafang C961, but I've done it with every other rinky dink LED and LCD display I own, maybe five different brands.

Put battery positive on P+ and battery negative on GND. Press the ON button and the LCD will turn on. At that point, it will connect battery positive to PL, You can probably change the PAS level to see if it works. With many controllers, getting power thru the PL pin is what turns them on, so the display is acting as an on/off switch.

RxD and TxD are serial data in and serial data out. Nothing happens there unless you have a working controller.

The speed sensor runs off a 5 volt supply in the controller, but the LCD display runs off battery. So while you could have fried the controller's 5 volts, that shouldn't stop the display from powering up.

 

[JWBrown]

So I pulled the controller. No sign of moisture, corrosion, damage or bad connections. And, of course, no way to test anything because it is all sealed and I wouldn't have any idea of what the electronics are anyway even if exposed.
So next, I want to test the display as you detail above, but one question before I put power to it: The female half (holes not pins) of the 5 pin connector runs to the display. The male half joins the larger 8 wire main cable running to the controller. Which half of the numbered 5 pin connector end does the schematic you sent show? I see it says "All pin-outs are from the main harness side of the connectors." But I want to be totally sure I understand that. Is the "main harness side" the controller side and the other side would be, in this case, the display side?

 

[harryS]

All pin outs are from the main harness side. That means that we're looking at the male connector that goes to the display, The female connector from the display will mirror it. It's better to have the holes. Easier to put wires in.

If I were to miswire it, putting battery/ground across P+ and PL instead of P+ and Gnd, it should be fail safe. Until the display powers up, P+ and PL are not yet connected, and that won't happen unless I connect the battery across P+ and Gnd.

The wiring diagram is from someone at Luna though, not Bafang.

 

[JWBrown]

Thank you for the clarification. I will next test the display.

 

[JWBrown]

Connecting 41 volts from the battery to the isolated display caused the it initially to light up all possible icons and then fade to only displaying 30 H (30 mph?) and a flashing motor icon and a flashing empty battery icon. I don't get the flashing drained battery indicator....

Curiously, I got no response when I connected to ground (#8) and P+ (#1). I then connected ground (#8) and PL (#2). That is when the display lit. This is when you look at the female plug which comes from the display and P+ is at 12 o'clock, ground is at 7 o'clock and PL is at 4 o'clock. So how can the display work when powered by #8 ground and #2 PL ?? Maybe the wiring of the BBSHD (diagram above) is different than my BBS01B?

 

[JWBrown]

HarryS
Thank you for past assistance with this problem. I ordered a new controller and speed sensor from GreenBikeKit. It took four and one half months to arrive. After installing the new controller and sensor, carefully checking all connections and load testing the fully charged battery, it still did not work.
So, I decided it might be the display. Not wanting to wait forever for another shipment from China, I ordered a new C961 (they don't carry a C965) display from bafangusadirect.com which is located near me in Orange County, CA. the delivery took two days. I Installed it and everything works fine. It was probably the display all along. Note in my original post about the appearance of moisture/clouding behind the C965 display glass despite no exposure to water that I was aware of. I think I will split the case on the old display and try to find evidence of corrosion. Will report here if I find that.