VNH5019 - problem going in reverse

One of my motors isn’t going in reverse. I’ve tested two different motors in both the M1 and M2 connections but the M2 connection refuses to go into reverse. Upon setting a multimeter onto the leads, there is no voltage when M2 is set to go into reverse. However, going forward there is a voltage. What could be causing this issue?

EDIT: I’m using an Arduino Mega 2560


My immediate suspicion is that you have a bad solder connection on M2INA or M2INB. Can you post some pictures of your setup and the simplest program that demonstrates the problem?

- Ben

Heres the setup I’m using and the program I downloaded from this website. I’m just using the setSpeed function. So I’ll type something such as md.setSpeeds(-400, 400); into the main part of the program (void loop) to make one of the motors go in reverse and it doesn’t work. I’ve tried both motors and reversed the leads as well but one of the connections won’t allow it to go into reverse. I’m not sure which motor control connection is bad at the moment as I don’t have the system with me.

They both will go one direction just fine and one connection will go in reverse. Also, I took a look at the soldering job and it seems okay but I’ll do a more thorough search tomorrow morning.

Let’s simplify the system even further. Can you disconnect your motors and just use the motor indicator LEDs for feedback? For example, what do you see from the motor indicator LEDs when you run the following loop() function:

void loop()
  md.setSpeeds(400, 0);  // m1 green LED should be on
  md.setSpeeds(-400, 0);  // m1 red LED should be on
  md.setSpeeds(0, 400);  // m2 green LED should be on
  md.setSpeeds(0, -400);  // m2 red LED should be on

Is there one LED that consistently will not light, and if so, which one is it?

- Ben