sw900 display

[BoBike]

First off this is used with 1500w Violamart hub motor kit with the built in controller. The problem is that when you shut down the display there is power still going to the motor. To narrow down the problem I hooked up a 830 display and when the display was off so was the motor. Contacted Violamart and they had some recovery business send me a replacement not sure it was new the long
and short of it same problem as the one that came with the kit. I also installed the replacement sw900 in my other ebike and same problem it would not cut the power to the motor. If anybody has any suggestions I would appreciate any advise.

 

[HazEbike]

On the sw900 with it unplugged from anything, place your multimeter in continuity mode and check between the red and blue pins on its harness, if it beeps then you have a short somewhere in the motor enable circuit on the display.

 

[amberwolf]

It's also possible that they didn't even include the switching circuit inside the display for the ones you got, and instead just wired straight across it. (either at the plug end, or inside the display).

It's not all that uncommon for the switch to fail in a way that prevents the controller from turning on, so if they got failed ones back from customers and then "fixed" them by wiring around the blown switch circut...this is what would happen.

The switch can also fail shorted, leaving the controller always on.

 

[TeslaHunter]

I recently had 2 SW900’s that developed continuity between the red and blue wires coming out of the display… (they worked fine initially)... This means that the throttle/controller is always powered whether the display is on or off… Is there anyway to fix the motor enable circuit on these displays? I really feel like it’s unsafe since grabbing the throttle with the bike off can cause it to lurch forward.... thanks in advance!

 

[TeslaHunter]

recently had 2 different SW900’s that developed continuity between the red and blue wires coming out of the display… (they worked fine initially)... This means that the throttle/controller is always powered whether the display is on or off…

Is there anyway to fix the motor enable circuit on these displays?

I really feel like it’s unsafe since grabbing the throttle with the display powered off can cause it to lurch forward.... thanks in advance!

 

[boytitan]

from my experience that happens when a controller is going bad. I had a controller do that and it would also short throttles out randomly.

 

[TeslaHunter]

Good to know... on both bikes currently everything else works fine...

 

[amberwolf]

You'd need to trace out and locate the transistor (probably a FET) that does the switching, and test to see if it's shorted on, or if it is just being held on by somethng else wrong in the display. If it's failed, you can just replace it with an equivalent part.


Alternatley you can install your own switch in series with one of those two KSI wires.