BBS HD power cutting off and on


New member
Local time
8:17 PM
Dec 29, 2022
Dec 22, 2022
hi all,

my bike has now become unuseable, sadly. motor has only done about 400 miles.
issue started with the PAS level changing by itself, especially (and probably exclusively) when using the throttle. what then started happening is the motor cutting off and on, sometimes only very briefly, other times the motor cuts and then only briefly cuts on/off again.
when it's happening, either the throttle works or it's non-responsive, doesn't seem any pattern to it.
on a test drive few weeks back, after dismantling button pod for PAS, it then performed fine until i used the throttle, then PAS would jump about, motor would cut etc.

i've swapped out the throttle, main wiring from where motor plugs into it, changed display and button pod, removed battery to check connections etc. and can't find anything that would cause this.

if anyone has any ideas at all, they would be much appreciated, as i'm coming to the conclusion it's something in the motor itself as i've replaced almost everything else.
i suspect it's not the battery, as the display never flickers/switches off , it remains on whether motor working or not. i suspect if it was a battery power/BMS issue the display would flicker etc.
there are no error codes on the display.

bizarrely yesterday when i fitted new display and button pod, took it for ten min test drive and it performed as expected, not a glitch. yet this morning tried to use it for work and got a few mins from house before motor hesitated a few times, then started cutting out entirely.

i do have a previous motor (with hall sensor failure) so have a spare controller, which is probably going to be next thing i swap. does anyone know if a controller can fail/cut in and out without error codes ?

Not really sure where to start, but these motors are "PAS: pedal assist, so are you running in a low range gear using the throttle only most of the time?? The first step is to replace the controller with the other controller and see if the motor operates, that means swapping out the internal controller in the motor and also replacing the display. Any other information as to riding conditions, hills,gear selection, etc. Also your brake levers could be the culprit, when brakes are applied motor cuts out. What model of display are you using. Can you unplug your brake cable and try to start the bike??Let me know, "baby steps here"
Definitely check the brake cutouts. Best to just disconnect them as noted above.

However, with additional issues like the PAS level changing by itself... thats not brake cutouts. I would have pointed to the next step being a replacement of the main wiring harness but you have already replaced everything but the motor controller... except what about the wiring on the motor side? Thats still going to resolve itself with a controller switch.

I would try the brake cutoffs, and plan on changing the controller in the same sitting, since you have already changed everything else out. If changing it makes the problem go away, look at the wiring harness connections on the bad controller as a possibility to bring it back into proper functionality.
For sure do that if you are pulling apart the motor internally. But if doing things like disconnecting the brake cutoffs, the display to get at the internal settings... external stuff. No worries there.

EDIT: I stand corrected. I know someone who did BBSxx primary tech support for many years and turns out they follow the same protocol for all wiring work, internal and external. Myself, I'll continue to not worry about exterior cabling but thats not best practice.