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HOMESERVICE MANUALSCHEVROLET2009TAHOE BASE, 4.8 CREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 574 (HVAC SYSTEM - AUTOMATIC)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B3933CIRCUIT/SYSTEM TESTING
2009 Chevrolet Tahoe Base, 4.8 C

Circuit/System Testing

2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the evaporator air temperature sensor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 5 Ω between the low reference circuit terminal B and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the HVAC control module.
    • If less than 5 Ω 
  3. Ignition ON
  4. Verify the scan tool A/C Evaporator Temperature Sensor parameter is less than -35°C (-39°F).
    • If -35°C (-39°F) or greater 
    1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module.
    2. Test for infinite resistance between the signal circuit terminal A and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the HVAC control module.
    • If less than -35°C (-39°F) 
  5. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B.
  6. Verify the scan tool A/C Evaporator Temperature Sensor parameter is greater than 85°C (185°F).
    • If 85°C (185°F) or less 
    1. Ignition OFF, disconnect the X3 harness connector at the HVAC control module, Ignition ON.
    2. Test for less than 1 V between the signal circuit terminal A and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the HVAC control module.
    • If greater than 85°C (185°F) 
  7. Test or replace the evaporator air temperature sensor.
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