Dual G2 High-Power Motor Driver Shield needs an arduino reset at startup

We have a problem with the Dual G2 High-Power Motor Driver 18v18 Shield : it works well except at startup where you have to reset the arduino. Indeed there is a motor runaway/racing at startup with our own code or nothing works with the example code and after a reset all works well in both case.

We can’t let it like that and we don 't understand why we need to do this reset. Could you help us please ?

Hello.

I am sorry you are having trouble getting your shield to work as you expect. Can you tell me more about your system? Which Arduino are you using? How are you supplying power? Can you link to the product page or datasheet for your motor? Can you also post pictures that clearly show the soldered joints on your shield?

-Jon

Hi, thanks for your reply.
Concerning your questions:

ps: 2nd attachment (back picture)

Can you try running the Demo sketch and look at the output of the Arduino IDE’s serial monitor while you do so? Is anything reported there? Also, have you tried or can you try with a different Arduino?

-Jon