The CRUX DKGM-15 is a premium interface for select General Motors Class II Vehicles. It facilitates the integration of an after-market radio to fully retain OnStar other factory features in GM Class II Data bus vehicles for Bose Amplified and Non-Amplified Systems. A double DIN radio replacement dash kit is included in the kit to make the installation quick and easy. The DKGM-15 interface is also pre-programmed for retention of steering wheel controls. DASH KIT INSTALLATION: A Double DIN radio replacement dash kit is included in the kit to make the installation quick and easy. Please make sure that you have all the parts written below (1) Main trim ring (1) Left ISO mounting bracket (1) Right ISO mounting bracket ONSTAR VOLUME ADJUSTMENT: To adjust the OnStar volume, turn on OnStar and adjust the volume using the Steering Wheel Control volume SELECTING THE AUDIO SYSTEM: If the vehicle is equipped with an amplified Audio System, the DKGM-15 has a built-in audio level adaptor that outputs the proper audio level from the aftermarket radio to the factory amplifier. To use this feature plug in the male 8-pin connector on the DKGM-15 harness to the GRAY female 8-pin connector on the DKGM-15 module. The module is also labeled “Bose” and “Non Bose” to avoid confusion. If the vehicle is NOT equipped with a factory amplified system, plug in the male 8-pin connector to the BLACK female 8-pin on the DKGM-15 module. CHIME VOLUME ADJUSTMENT: The DKGM-15 has a potentiometer to adjust the chime volume. It is set at half way by default. To adjust the volume, simply use a suitable screw driver and turn the potentiometer clockwise to increase the volume and counter-clockwise to decrease the volume.