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 harness connector at the coolant heater temperature sensor.
- Ignition OFF, test for less than 5 ohms between the low reference circuit and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the coolant heater.
- Ignition ON, verify the scan tool Overheat Temperature Sensor parameter is greater than 4.5 volts.
- If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the coolant heater.
- Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool Overheat Temperature Sensor parameter is less than 0.5 volts.
- If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the coolant heater.
- If all circuits test normal, test or replace the coolant temperature sensor.