JRK 21v3 motor driver error

I’m trying to use my jrk21v3 to control a windshield wiper motor. I have measured with my fluke multimeter that the max current draw on start up is 4.1 amps and the current draw after startup is 0.6-0.7 amps. I keep having this situation where when I go from 100% to 0% duty cycle quickly or if I try to quickly reverse the direction of the motor I get a motor driver error, and even though I do not have the motor driver error set to latch the board will not go back to functioning afterwards, the error will go away but it will still not turn the motor and then a couple seconds later the no power error will come on and stay on even though the power supply is still on and the error will stay on until I turn the power off and back on. Any info helps, thanks!


The motor driver error occurs on under-voltage, over-temperature, or over-current conditions. It sounds likely that it is the over-current condition being triggered from your description.

When you measure the start-up current with your meter, is it set to a mode to measure the peak current draw? If not, and it is continuously displaying the current draw, please note that the start-up current spike can be very brief, so the meter is likely not showing the highest value.

The current draw when going from full-speed in one direction to full-speed in the other can be upwards of twice the stall current (which being at least 8A would be much higher than what the jrk 21v3 is rated to handle). Are you using position feedback with your wiper motor? If so, the motor could be switching directions rapidly (depending on your PID tuning). You might try setting the “Max. acceleration” value in the “Motor” tab of the Jrk Configuration Utility to something low like 10 or 20 and seeing if the problem still occurs.

By the way, what are you using as a power supply? The motor driver error could also happen when the motor power becomes disconnected while the jrk is connected to USB. It seems less likely, but if your motor draws enough current, it could cause your power supply voltage to drop low enough for this to trigger.


Brandon, I was using a peak recall function on my meter to see what the max current draw was when all this was going on and that’s how I got the 4.1 amps. After some more troubleshooting, I disconnected the USB cable and repeated the same tests and found that the board would turn off all together when this happens. This lead to me putting the multimeter directly on the power supply and discovering that it was in fact my power supply that was tripping when this was happening. Since it’s a 15 amp power supply and both my meter and the board show current staying under 5 amps I guess it’s just a faulty supply. Thanks for the help!

Thank you for letting us know what you found. If you still have problems with errors showing up after replacing your power supply, I would be happy to continue troubleshooting.


Hey Brandon, I have a potentiometer connected to my motor as feedback. I was wondering what would be the best way to limit the travel of the system with the software settings. I would like to limit the motor to 90* of travel but I’m not sure if I would configure this in the feedback tab or input or somewhere else, and what specific fields I would target to achieve that.

Thanks, Andrew.

You can limit the motion by changing the way the input scales to the feedback. This can be done by changing the values in the “Scaling” sections of the “Input” tab of the Jrk Configuration Utility. To limit the motion, you can lower the “Maximum” value in the “Target” column of the scaling options.

Alternatively, you could change the feedback scaling options in the “Feedback” tab of the Jrk Configuration Utility. One way to do this would be to use the “Learn…” button, and when it asks you to put the motor in the maximum (full forward) position, you can put it in the 90-degree point.