It's easy to tell if it's programming vs electrical in nature.
There are Relay status LEDs (a red/green for each Relay) on the Digital Sidecar that tell you exactly what the code is commanding.
It doesn't matter if the Spike is attached or not.
If your code is working correctly to command Forward and Reverse, then the Relay LED for the proper Relay will show:
- Off = both LEDs off (dark)
- On = both LEDs on (red & green), not used for motors
- Forward = green LED lit
- Reverse = red LED lit