Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
Ambient / Inside Air Temperature Sensor Circuit Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
- Test for less than 1 ohm between the low reference circuit terminal B 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 HVAC control module.
- Ignition ON, verify the appropriate scan tool Temp Sensor parameter is greater than 4.9 volts or 250 counts.
- If less than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
- Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Temp Sensor parameter is less than 0.1 volt or 5 counts.
- 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 HVAC control module.
- If all circuits test normal, test or replace the appropriate temperature sensor.
Duct Temperature Sensor Circuit Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
- Test for less than 1.0 ohm between the low reference circuit terminal 2 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 HVAC control module.
- Ignition ON, verify the appropriate Duct Temp Sensor Actual parameter is greater than 4.9 volts or 250 counts.
- If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the HVAC control module.
- Install a 3-amp fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool Duct Temp Sensor Actual parameter is less than 0.1 volt or 5 counts.
- 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 HVAC control module.
- If all circuits test normal, test or replace the appropriate temperature sensor.