It's important to note that you must first have a JourneyTek EP001, EP004 etc pickup to plug into this module. So to start, make sure that your passive piezo unit is functioning properly.
Firstly, make sure you have switched to the new updated output jack that's included with the EPS001 kit. Some of the older EP001 pickup jacks aren't compatible, so we include a new one in the active pickup kit.
Secondly, check your battery power and confirm the cable from the battery to the main module is fully clicked-in. If you're low on power, the unit won't function properly.
Thirdly, with the "v" volume wheel turned up, check the wheel position for “P” for “Pan” between the mic and piezo channels. If the pan setting is set fully towards the microphone, you’ll only pick up the microphone and not the piezo. If it’s turned fully toward the piezo, you’ll only hear the piezo and not the microphone. If it’s in the middle you’ll get both signals.  Plug the unit in, and dial this knob from left to right and see if you get signal from both piezo and microphone channels.
Finally, there are two connections you need to double check:
1) Double-check the connection from the 3 piezos to the main module (press in fully, and twist a little).
2)  Check the connection from the main unit to the output jack (both at the main unit, and at the output hack - check connections at both locations. This internal cable is a stereo cable and if it’s not fully connected, it will not function properly.
After you’ve double-checked these connections, go back and increase the volume dial and turn the Pan dial back and forth. This usually solves 99% of connection issues.