If your vehicle is showing dashboard clock keeps resetting to 12:00, here are the most likely causes and the parts you'll need to fix each one.
When the battery is weak, the voltage drops drastically while cranking the engine. This sudden drop starves the dashboard electronics of power, causing the clock's keep-alive memory to reset.
Poor connections at the battery restrict current flow. The heavy electrical draw of starting the engine or physical jarring from hitting a bump can momentarily break the circuit, resetting the clock.
The clock relies on a constant-power fuse (often labeled 'ROOM', 'DOME', or 'BACKUP') to keep time when the car is off. If this fuse is loose, blown, or has poor contact, the clock loses its memory immediately upon shutoff.
If the alternator isn't properly charging the battery while driving, the battery voltage will slowly deplete. This low voltage state eventually causes memory loss in dashboard electronics.
The internal circuitry or memory capacitor inside the dashboard or body control module has failed, preventing it from retaining the time even when receiving proper voltage.