GM Service Manual Online
For 1990-2009 cars only

The selectable ride (SR) suspension system allows the driver to choose between 2 distinct damping levels, firm and normal.

The SR dampers are gas charged units which provide damping by forcing hydraulic fluid through internal orifices within each shock in order to resist suspension movement. Each shock contains an internal solenoid actuator that the SR switch controls. This solenoid actuator controls the size of the orifice that the hydraulic fluid is forced through, thus altering the ride characteristics of the vehicle.

Voltage is supplied to the switch via the ignition 1 voltage circuit from the SEO IGN Fuse. When the system is on, the voltage is supplied to terminal  A of each shock providing firmer damping. Ground is supplied to terminal B of each shock.