Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I hope to be able to straighten out the situation with good advice. But first I need to get a little more information about the case, please:
- is the P66 transducer, plugged into the GPS 400S (presumably) by its own cable, or through an extender cable, or a network backbone, or otherwise?
- is the P66 a transducer made by Airmar ?
- what port on the Garmin GPS 400S is the cable from the P66 plugged in to?