After disconnecting the battery for a maintenance job, I had some clueless days while trying to reset the clock in a car audio system. Even though there should be a way to set the clock in audio systems it is bit difficult to find it without the manual of the system.
My in my scenario I found it after sometime, so thought to share it since it might help someone with the same problem.
Car audio system in which I had the issue was JVC KD-S5055.
To start the resetting you need to press and hold the “Select” button for about 5 seconds. Then a message similar to “Hour-h” will be shown in the display. Once this appears use the + and – buttons located on the left to set the hour value of the time.
Then to set the minute value you need to press the mode change buttons located on the right side. Once you press the mode change button while on the hour changing mode you will see a message similar to “Minute-m”. Then again you can use the + and – buttons to set the minutes portion of the time.
After successfully setting both hour portion and minute portion you can press the Select button again to save the changes made to he clock.
Additionally if you need the system to show the time when the device is switched on you can press the Display button located below the Select button. This will show the current time instead of the Radio/CD/Track information.
Hope this helps.