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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (HVAC - Manual) >> Diagnostic Information and Procedures >> DTC B0449, B0450, B0451, or B0452 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF, disconnect the harness connector at the blower motor.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal and ground.
    • If greater than the specified range, replace the coolant heater.
  3. Install a test lamp between the control circuit terminal and low reference circuit terminal.
  4. Ignition ON, command the blower motor ON and OFF using a scan tool. Verify the test lamp turns ON and OFF with each command.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the coolant heater.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the coolant heater.
  5. If all circuits test normal, test or replace the blower motor.
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