Inflatable Restraint Side Impact Sensor (SIS) (right) with RPO HP2
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 right side impact sensor (SIS) contains a sensing device which monitors vehicle acceleration and velocity changes to detect side collisions that are severe enough to warrant disabling the 42-volt system. The SIS is not part of the deployment loop, but instead provides an input to the sensing and diagnostic module (SDM). When the SDM receives a signal from the SIS that a collision has occurred, the SDM communicates this over the vehicles communication bus. The module responsible for the 42-volt system receives this message and disables the 42-volt system.