Depending on how old your vehicle is and the make of chassis, the following may help. It worked on our 2013 Peugeot based Autosleeper and switches between normal mode and camper mode, giving you up to 3 hours of radio before it switches off ( presumably to help save your
battery)
it may or may not work on yours.
1) Turn radio ‘ON’ using the central ‘power’ button
2) Within 15 seconds, simultaneously press ‘FM AS’ and the preset button ‘2’. Each time this pair of buttons are pressed, the display will alternate between ‘NORMAL POWER MODE’ and ‘CAMPER POWER MODE’.
(note these must be pressed together for upto 5 seconds)
3) Ensure that ‘CAMPER POWER MODE’ is displayed, then press ‘MENU’
4) Using the ‘UP and ‘DOWN’ button now changes the display to show various adjustable items. Cycle through the options until ‘RADIO OFF’ and a number of minutes is shown on the display. This will take approx. two presses of the ‘UP’ button or seven presses of the ‘DOWN’ button.
5) With ‘RADIO OFF’ shown on the display press the ‘LEFT’ or ‘RIGHT’ button. Each press of either button will alternate the number of minutes shown between ‘180’ and ‘0’
6) With ‘180’ showing on the display the setting is complete and three hours of radio operation should be possible. Press the ‘POWER’ button to exit the menu and return the display to its usual view.
Please note that in ‘NORMAL POWER MODE’ the same subsequent steps detailed above can be followed, to choose between ’20 mins’ and ‘0 mins’ of radio operation.
i might add that, although I carried out this mod, we never used the radio more than a couple of times while in the UK, we spend most of our time in France and the radio only picked up French commercial stations, which are worse than UK local radio......