Circuit/System Testing
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.
- Ignition OFF, disconnect the Rap relay.
- Connect a test lamp between the relay coil control circuit terminal and ground.
- Cycle the ignition ON and OFF. The test lamp should turn ON and OFF when changing ignition switch positions.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.
- If the test lamp illuminates normal, test or replace the Rap relay.