If you want to de-activate the security code on the radio, the following steps will stop the need for you to input the code after a battery disconnect, however, this isn't a way of getting round unlocking it if you've lost the code, as you need to know what the code is in the first place, in order to disable it for the future.
For the Philips Harmony Radio:
The security function is deactivated by holding the radio tuning search up button depressed while switching on the unit using the push on/off rotary volume control.
Security code input will be requested on the LCD and audio output will be muted. Once the security code is successfully input, the audio output will be restored and the security code function will be disabled.
The security code can be reactivated by holding the radio tuning search up button depressed while switching on the unit using the push on/off rotary volume control. A
'CODE ENABLED' message will be displayed on the LCD for approximately two seconds.
For the Alpine Symphony Radio:
The security function is deactivated by holding the radio tuning search up button depressed while switching on the unit using the push on/off rotary volume control.
Security code input will be requested on the LCD and audio output will be muted. Once the security code is successfully input, the audio output will be restored,
'CODE OFF' will appear briefly on the LCD, the unit will emit two 'beeps' and the security code function will be disabled.
The security code can be reactivated by holding the radio tuning search up button depressed while switching on the unit using the push on/off rotary volume control. A
'CODE ON' message will be displayed on the LCD for approximately two seconds after two warning 'beeps'.
The Highline Sat Nav radio does not have a security code to worry about.
How a To Disable Your Radio Security Code