Aygo: Radio does not turn off + function keys cannot be operated

September 12, 2022

Hello everyone,

I've had a problem with my radio on my Toyota Aygo AB10, built in 2005, petrol engine, for the past day. After driving with the radio switched off, the radio switched on after about 2 seconds after switching off the car and removing the ignition key. The audio system was set as it was when the system was last used: CD playing and quite high volume. None of the radio buttons could be operated except for the CD eject button. The radio could be heard after the CD was ejected. Again, no change could be achieved by pressing the buttons, opening the door or starting and switching off the car. After about 2 hours the radio goes off. The problem with the buttons is the same whether the car is on or off. Each time the car is turned off, the radio is off for about 2 seconds before turning on again. The car has always started again. The Battery is about 1 year old. The radio is the original radio (see pictures) and has never been modified or repaired. No repairs or modifications have been made to the car in recent months. There are no indicator lights on. About half a day after the problem occurred, a technician from the breakdown service was there to check the problem. The technician was very young and, according to his own statement, still somewhat inexperienced with such problems. He couldn't find the problem but pulled fuse #12 (fuse was good). I have uploaded an overview of the fuses and their assignment as a photo, but it is in German (p. 284). The text for fuse #12 says "Display and measuring devices, interior light, audio system, tachometer". By pulling the fuse, the radio, the interior light and the indicator light for the low beam are now permanently off. What's funny to me is that shortly before the technician arrived, the volume buttons worked again, while, for example, the channel selection buttons and the on/off switch still didn't work.

I haven't found a solution to this problem either here or on other forums. But I found out during my research that the problem "Ignition off, radio stays on" is often due to 1. the wiring of the radio, 2. the ignition switch, 3. the key or lock or 4. the programming of the radio . Reason 2 and 3 sound like a problem with turning the radio on and off to me, but wouldn't explain the (changing) non-functioning of the buttons. Reason 1 can probably occur when a new radio has been installed, which is not the case here. Reason 4, the programming of the radio, was not changed either. So I'm a bit perplexed.

Question: Does anyone of you have an idea what could be causing this audio system malfunction?