The 2005 Volkswagen Beetle GLS Convertible comes standard with a Monsoon AM/FM radio with CD player and MP3 player. The MP3 player is utilised by plugging a device into the auxiliary input jack via the device's headphone output jack, and then selecting the AUX input option on the radio. The cable required for this has standard 2.5mm plugs (headphone plugs) on either end.
Locate the heated seat controls on the vehicle's main dash.
Look for a small, metal-edged hole underneath the passenger side heated seat control.
Plug one end of the 2.5mm cable into that jack, and the other end into the headphone output jack on your MP3 device.
Press the CD button on the radio several times until the screen displays "AUX." Your MP3 device should now play through the car's stereo.