I have a Toyota 7FBCU25 electric counter balance. It had error code 51-1, I change both board on left side on control panel and code went away. I try driving unit but it wont past 1kpm and move very slow and battery bark blinking.

Can anyone help please.

If I remember correctly the sensor is in the bearing. I had no way to test it, I replaced it and everything was fine.

What does the speed sensor look like and how do you test it?

thanks rick,
it was the sensor

lets start from the beginning, does the wheel turn freely with the motor in place. if you pushed the unit would it roll? if the answer to both of these questions is yes and the motor is still out replace the speed sensor. it is the bearing with the wires on it. it is possible but difficult to test out of the unit and too cheap to mess with. once you have determined that this is not mechanical, reinstall the motor with the new bearing and test the unit. if problem is still present swap the two controllers on the left side of the truck (sitting on it) if it is a controller the problem will change sides.

rick c ,
how can i test the sensors, i still have the motor out.
would a fault code come up ?
there are 2 small wires comming out of the motor
thanks

the motor may be fine but most rebuilders dont know anything about the speed sensors and when they go bad the controller cant detect direction and "locked up" is what happens