Circuit/System Description
WARNING: This page is about a different car, the 2012 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.
The hybrid/EV powertrain control module 2 monitors the date and time data it receives from the GPS satellite systems via the OnStar module. This time information is used to ensure the module's internal clock is synchronized to the customer's local time. The Time of Day Charging feature utilizes this internal clock to keep track of time and alarms for delayed charging modes. If this GPS time data is received during a drive cycle, the system is considered synchronized.