Diagnostic system for a vehicle electrical system

A diagnostic system for a vehicle electrical system, the vehicle electrical system having a battery module, a contactor, a high side driver circuit, and a low side driver circuit, comprising:

• a high side voltage measuring circuit being electrically coupled to the high side driver circuit and to a first input port of a first analog multiplexer;
• the high side voltage measuring circuit generating a high side voltage level signal corresponding to a high side voltage being applied to a contactor coil of the contactor, the high side voltage level signal being received by the first input port;
• a low side current measuring circuit being electrically coupled to the low side driver circuit, and further electrically coupled to a second input port of a second analog multiplexer;
• the low side current measuring circuit generating a low side current level signal corresponding to an amount of electrical current flowing through the contactor coil that is received by the second input port;
• an analog-to-digital converter being electrically coupled to an output port of the first analog multiplexer and an output port of the second analog multiplexer, the analog-to-digital converter receiving the high side voltage level signal and the low side current level signal at first and second times, respectively, and outputs a high side voltage value and a low side current value, respectively, based on the high side voltage level signal and the low side current level signal, respectively, that are received by a microcontroller;
• and
• the microcontroller commanding the high side driver circuit and the low side driver circuit to transition a contact of the contactor to an open operational position when the first analog multiplexer is malfunctioning based on the high side voltage value.