The middle light of these five LED's indicates proper tuning. Tune all your strings to the GR-09 using this method. Release the S1 button and press Pedals 1-4 to choose the desired Patch. The Pedals can be used to control Pitch Shift, Modulation, Hold 1 and Hold 2. Pitch Shift will raise or lower the pitch of the synth sound.
Modulation adds vibrato to the current synth sound.
Both the Hold 1 and 2 functions are used for sustaining the synth sound of the GR-09. The Hold 1 function will sustain currently active synth notes and let you play the guitar sound on top. The Hold 2 function will sustain only the currently held strings and let you play guitar or synth sound on top. Pdl' will appear in the display. Pedals 1 thru 4 will now function as Pitch Shift, Modulation, Hold 1 and Hold 2.