Your battery terminals are most likely corroded or loose, but if you have no trouble starting the engine your radio constant power wire may be hooked up to a circuit that only works with the key on.
if you have a after market radio in your car your ground wire is lose or not hooked at all.
there is no problem you just lose all preset stations and any equalizer settings everything returns to default settings after a power loss you must reset all settings manually.
the memory wire is either not hooked up or is connected to a keyed hot that only has power when the ignition switch is on
Usually a sighn of bad alternator.
Believe it or Not You have to Change your Spark Plug and Distributor Wires, to Noise suppressor type wires and probably put in a noise suppressor filter in the Hot wire that runs the Stereo. I know it sound different but this works.
A diesel engine that is starved for fuel will lose prime. This means that you will be unable to start the engine once it has stalled.
If the CMOS battery dies you lose the settings that are held in the BIOS (Basic Input Output System). These include settings such as date/time, boot order,etc.
easy way is to disconnect the battery Answer #2: There is not just one 'computer' on this vehicle. Settings are maintained at various locations throughout the vehicle. Generally each component which has settings, contains an eprom to preserve those settings. For example: The radio will not lose its settings if the battery is disconnected. What does "reset" mean? I believe you need a laptop or other computing device with the appropriate software to be able to modify the settings of the vehicle. Some devices must be configured at a dealer. This helps protect against radio theft etc.
Perhaps alternator is not charging battery properly - check with a voltmeter a fully charged battery should read approx. 12.8 volts without engine running with engine running reading should be approx. 13.8-14.2 volts
You will lose everything! Apps, contacts, music, and personal settings.
Disconnect positive battery terminal for approximately 10 minutes. If there is really no problem, light will not stay lit after start up. You will lose clock settings. I did this when mine came on and reported DTC 55 which is just an "end of list" indicator.
Nothing, the computer will run fine on the default settings usually.