I think he means the DISPLAY is always on.. and that would drain a battery in a couple weeks
If the actual radio turns off with the key off then I doubt the problem is in the ign switch
There are three power inputs to a typical radio:
Always on - to hold presets and power clock logic. If you find the fuse for this and pull it i'm betting the display will go off.
Accessory - provides radio operating power and drives basic display illumination
Instrument lighting - which controls radio panel illum and affects display brightness indirectly
Obviously the clock is always running when the battery is connected, it uses the same input as preset memory and doesnt use any power to speak of. But the display should not be lit.
Added Note: See below, the problem is indeed associated with a chip.
Makes sense that all functional switching be done in a big chip and that includes radio function logic. It doesnt take any more power than a watch or phone memory so why not just run that chip all the time. I suspect re is a shorted output gate the chip that should tell the display power to turn on or off.
What has probably happened here is that a diode or transistor inside the radio has failed and the clock display is pulling power from the memory power supply.
Mind that the failure could actually be inside a chip. Practical fix then is to replace the radio. Cutting the wire that supplies it would require resetting stations every time you turn off the car.
Last edited by pettyfog; 08-15-2011 at 12:03 PM.