Help with DualMC33926MotorShield

my DualMC33926MotorShield was working, but suddenly stopped. i have loaded the demo program, and nothing happens if the motors are connected. if i disconnect the motors, the indicator lights come on and off as expected for the demo program. if i leave one motor connected. the lights cycle once on the disconnected side, then there is a brief flicker of the green LED on the connected side…then nothing, and the lights on the disconnected side no longer function. im using two(2) 25D gearmotors(12v, high power, 20.4/1 ratio) and powering the unit with a 12v, 5ah lead acid battery. any assistance would be appreciated!

Mike Carey

Hello, Mike.

Could you tell me more about your setup? How long did the shield work before you saw this issue? What happened between when it was working and when it stopped? If you power the gearmotors directly, do the gearmotors run? Could you post pictures of your setup showing the connections and the soldering?


Hi grant, thanks for responding! This is a BB-8 droid project. I’m running the shield off an arguing uno r3. I’m using an hc-05 Bluetooth module to control the droid with my android phone. I’m powering the project with a 12v, 5ah lead acid battery. I just got it up and running the other day, and it probably only ran for a total of about 10 minutes before it stopped working. It was operating normally, then just quit. I was only operating the motors on about half speed(by the android app) as full speed was way too fast. The lead acid battery is suspended under the platform for balance reasons(chose lead acid over lithium for this reason…needed the extra weight down low for balance). I did connect the motor directly to the battery, and it ran fine. My conclusion is that the driver shield has stopped working for some reason, seems to fail if there is a current draw on the shield. As I said, the diagnostic motor lights work properly with the demo program, so long as the motors are not connected to the shield. Connecting them seems to “break” it and it locks up until powered down and motors are disconnected, then the lights work again.

Here are some pictures


Have you checked the battery to make sure it has a full charge? Could you describe in more detail what the robot was doing when it stopped working? Was it just traveling forward? Was it switching directions to trying to balance in place?


I completely recharged the battery, but there was no change. I believe it was moving in a straight line at the time it stopped, but my daughter was controlling it, and I’m not sure what command she was sending it when it stopped. The motors are not involved in balancing, it uses the battery mounted low as a counterweight. It seemed to be operating normally…then just died. As I said it ran for a total of maybe 10 minutes…probably less, and not 10 minutes all at once, was testing it out and ran it for a couple minutes each time. As I said, mostly at about half speed, bumped it up to full a few times…but was too fast.

Do you have any other motors you could try with the motor driver? If so, do they have the same problem?


Unfortunately no…these are the only motors I have. I highly doubt the problem is the motors, the likelihood of the both failing at the same time is almost impossible…plus if I hook them directly to the battery, they operate just fine.

At this point I am not sure what is causing the issue. If you would like to try again, I might be able to get you a discount on a replacement motor driver shield. Please email us directly at with you order information.