Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The starter generator control module (SGCM) uses the interlock circuit to monitor the plugs and connectors for hybrid system function. The interlock indicates the state of the connectors in the 120 voltage circuits. In the SGCM, the primary side of the transformer is connected to a low frequency oscillator circuit. When the loop is complete, the shorted secondary reduces the oscillator voltage, and a comparator senses this as a good and complete interlock loop. If the loop is open, the oscillator amplitude increases and the comparator senses this as a problem.