The PCS SFT-4001 Gauge Driver Controlled Reverse Light and Neutral Safety Kit is only setup for the GMLAN CAN bus. The SFT-4001 gauge module reads the transmissions range position for Park Neutral and Reverse via CAN messaging to activate the individual relays. There are two relays, one for reverse lights and one park/neutral. The module will enter Scanning Mode every time the vehicle is keyed on. It will continually monitor the CAN bus for the transmission range state as long it is powered up. The gauge module uses low side drivers to ground the relays to activate the corresponding circuits. This kit is also available with a single relay setup. You can choose to have it setup for a park/neutral or reverse light kit only.