DTC P1510: Engine Control Module Back-Up Power Supply Malfunction: Description
WARNING: This page is about a different car, the 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
Battery voltage is supplied to Engine Control Module (ECM) so that DTC memory, engine performance "learned values", etc. are stored in ECM after ignition is turned off.