T,
The cable is almost never bad...
Step one is to see of the com port is working at all.. Use ScreenLogic or your remote and turn on a pool light. Confirm that ScreenLogic or your remote shows the light as on. Go out to the pool and ensure the light is really on. Using the outside main panel, turn off the light. Confirm the light is really off. Ensure ScreenLogic or your remote now shows the light as off.
If the above test works, it means that your com port is working.
Most of the time when the pump does not say "Display not active" the entire com port is not working. (You have to be in AUTO and not the Service mode.)
If the rest of the com port is working and the pump is not, then it has to be an issue with the pump, or the connection to the pump.
If this is a new IntelliFlo VSF pump, it could have bad Firmware. If an older pump, then that will not be the problem.
It could be the connector pins on the pump side. We have seen them corrode to a point they are almost not there. So I would inspect the connector and clean the pins if needed.
Please let me know if the whole com port is not working and we can do some more tests.
Thanks,
Jim R.