Circuit/System Description
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
The positive crankcase ventilation heater is controlled by the ECM. Ignition voltage is directly supplied to the positive crankcase ventilation heater and the ECM provides a controlled ground circuit.