 Sonnet has an indicator light on top of the processor. A short green blink indicates that the fine tuner command has been successfully received. A green blink indicates that Program 1 is selected. Two green blinks indicates that Program 2 is selected. Three green blinks indicates that Program 3 is selected. Four green blinks indicates that Program 4 is selected. If the optional status light has been activated, a short green light will blink every 3.5 seconds to indicate that Sonnet is initialized and working. Continuous red blinks indicate the batteries are empty and should be replaced. A continuous red light indicates that either minimum or maximum volume or microphone sensitivity has been reached. DL coil indicator lights The DL coil features a bi-color LED indicator light. If the DL coil is properly connected to the implant, the indicator lights will appear. Three short green blinks indicate that the DL coil, coil cable and audio processor are working. Your audio processor and implant are successfully connected. This is applicable to Synchrony, Concerto, Med-L Concert, Sonata and Pulsar implants. One short green blink indicates that the DL coil, coil cable and audio processor are working. This is only applicable to C40 Plus and C40 implants. No light indicates that either the link check feature has been disabled or Sonnet isn't working properly. Change the batteries. If no indicator lights appear after placing the coil over the implant, replace the coil cable. If an indicator light still does not appear, contact your CI center. Continuous short red blinks indicate the DL coil is not communicating with the implant. Ensure the DL coil is positioned over the correct implant. If the problem persists, try replacing the coil cable. Short red blinks 10 seconds apart indicate the DL coil has powered off. Turn your Sonnet off and back on and reposition the DL coil over the implant. Any other signals may indicate that the coil cable is defective. Replace the coil cable and if a problem persists, contact your CI center.