Section 65 (Power Assisted System Power Steering (Diagnostics)): General Description: Inspection: Battery
WARNING: This page is about a different car, the 2014 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
Measure the battery voltage and check electrolyte.
Standard voltage: 12 V or more (must not drop below 10 V during operation under electrical load)
Specific gravity: 1.260 or more