1. A circuit, comprising: a first differential amplifier (DA) configured to detect a voltage V 1 at a first voltage divider, said first voltage divider coupled to a chassis and to a positive terminal of a high voltage energy storage device (ESD); a second DA configured to detect a voltage V 2 at a second voltage divider, said second voltage divider coupled to said chassis and to a negative terminal of said ESD; a first analog-to-digital converter (ADC) configured to digitize said V 1 voltage to provide a V 1 value, and digitize said V 2 voltage to provide a V 2 value; a third voltage divider coupled to said ESD positive and negative voltage terminals; a second ADC configured to digitize a voltage V 3 detected at said third voltage divider to provide a V 3 value; a digital processor configured to use said V 3 value to calculate a VT value representing a voltage between said positive and negative terminals; wherein said digital processor is configured to use said VT value to calculate a checkproduct CP; wherein said digital processor is configured to add said V 1 and V 2 values to provide a sum VS; and wherein said digital processor is configured to compare said VS to said CP to determine whether a circuit fault exists.