Brake sensor constantly on (low voltage from controller)

[chris_m]

I just installed a new kit, but the display shows the brake sensor symbol and the bike won't run.

It's a KT-LCD5 and the controller is from PSW Power KT36/48SVPR-17A

I have unplugged everything, checked all the soldering and wires inside and outside the box. All looks fine.
Voltage between signal (yellow) and GND (black) shows 0.7V (where I understand it should be 5V).

On a few occasions after power on, the light has not been on, sometimes twice in a row. But then it comes on again after the next power on, and stays on.

Any ideas? I'm going crazy here.

 

[Drunkskunk]

The yellow wire is a signal wire, not a +5 supply. Check red to black on that plug for 5v on that plug.
When you saw that 0.7v, was the brake connected? If so, what does it read when the brake is disconnected?

 

[chris_m]

Oh, sorry. Was checking voltage between signal and ground bc that's the only two cables that are used by the brake levers.
I checked now. black to red is 4.30V. Signal to Gnd is 0.68 when connected and brake is not engaged, and drops to 0.02 when brake lever is engaged.

 

[E-HP]

I just installed a new kit, but the display shows the brake sensor symbol and the bike won't run.

Will it run with the brakes unplugged?

 

[chris_m]

No, same problem (brake symbol showing on LCD) when brakes are unplugged. And it won't run.

 

[Drunkskunk]

Odd. That 4.3 volts doesn't sound good at all. it should be 5 volts, and stabilized to stay at 5 volts.
You might want to check the other 5 volt lines, at the Hall sensor connector, Pedelec connector, and throttle. low voltage at all of those might mean a fault in the controller.

 

[chris_m]

I checked all the connectors and it's 4.37V on all of them.
Could this really mean the controller is a lemon?