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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System - Manual >> Diagnostic Information and Procedures >> DTC B048D or B048E: Auxiliary Heater Temperature Command Circuit >> Circuit/System Testing >> Electrical Auxiliary Heater Control Circuit Malfunction

Electrical Auxiliary Heater Control Circuit Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the E40 Electrical Auxiliary Heater. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the B+ circuit terminal 1 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the E40 Electrical Auxiliary Heater.
    • If the test lamp illuminates 
  5. Ignition OFF, remove the test lamp and disconnect the X1 harness connector at the E40 Electrical Auxiliary Heater, ignition ON.
  6. Verify a test lamp illuminates between the ignition circuit terminal 2 X1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the ignition circuit terminal 2 X1 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the E40 Electrical Auxiliary Heater.
    • If the test lamp illuminates 
  7. Remove the test lamp.
  8. Verify the scan tool Auxiliary Heater Output Status parameter changes from Malfunction to OK when connecting a fused jumper wire between terminal 4 X1 and ground.
    • If the parameter does not change from Malfunction to OK 
    1. Ignition OFF, remove the jumper wire and disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit terminal 5 X2 at the K33 HVAC Control Module harness connector and ground.
      • If greater than 1 V 

        Repair the short to voltage on the circuit.

      • If less than 1 V 
    3. Ignition OFF.
    4. Test for infinite resistance between the control circuit terminal 5 X2 at the K33 HVAC Control Module harness connector and ground.
      • If less than infinite resistance 

        Repair the short to ground on the circuit.

      • If infinite resistance 
    5. Test for less than 2 Ω between the K33 HVAC Control Module control circuit terminal 5 X2 and control circuit terminal 4 X1 at the E40 Electrical Auxiliary Heater harness connector.
      • If greater than 2 Ω 

        Repair the open/high resistance in the circuit.

      • If less than 2 Ω 
    6. Replace the K33 HVAC Control Module.
    • If the parameter does change from Malfunction to OK 
  9. Ignition OFF, remove the test lamp and disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
  10. Test for less than 1 V between the control circuit terminal 7 X2 at the K33 HVAC Control Module harness connector and ground.
    • If greater than 1 V 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  11. Ignition OFF.
  12. Test for infinite resistance between the control circuit terminal 7 X2 at the K33 HVAC Control Module harness connector and ground.
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • If infinite resistance 
  13. Test for less than 2 Ω between the K33 HVAC Control Module control circuit terminal 7 X2 and control circuit terminal 1 X1 at the E40 Electrical Auxiliary Heater harness connector.
    • If greater than 2 Ω 

      Repair the open/high resistance in the circuit.

    • If less than 2 Ω 
  14. Replace the E40 Electrical Auxiliary Heater and verify the DTC does not reset.
    • If DTC resets 

      Replace the K33 HVAC Control Module.

    • If DTC does not reset 
  15. All OK.
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