The e-bike with the front motor doesn't run, the contacts were shorted. What to do?


1 mW
Nov 16, 2023
Czech Republic
Hi, the bike had an H9 error, I found that 3 wires were shorted. I disconnected the wires and the error disappeared from the display. But the bike still doesn't run.

Could the short circuit have damaged the controller?
Is there any way to repair the controller? I'm an electrician.

How do I find a fault in this type of controller?
Thank you.


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If you disconnected the wires then it probably won’t work depending on what they go to, do you mean you disconnected them from each other? If that’s the case the wires could be damaged, check with a multimeter on both ends of the wire to see if it’s still got continuity. Sorry it that sounds really obvious to an electrician, just trying to provide common fixes or something you might’ve forgotten to check.
It’s possible the controller is damaged but most can usually handle a few shorts before blowing up (unless it’s a cheap aliexpress special which that one appears to be) Check inside to see if there’s any clear stains in the circuitry like a blown fuse or charred PCB spots. If nothing’s obvious you can try the oven method as a last resort before buying a new one.
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The wires that were shorted were your phase wires. Those are driven by Mosfet transistor like these, and they probably blew up when they saw the short circuit, I would suggest you buy a replacement controller of the same kind if you can find one. If you try a different controller, you also have to buy the matching display,, because displays are not universal. They are matched to the controller.

If you're skilled at working with circuits, you can try replacing all the MOSFET's, in the hope that their support circuits still work. On some controller cases, the top lid is removeable, making it easier to remove the heat sink and slide the circuit board out,

I have never tried to repair a controller board, They only cost $25-35 USD,