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Home >> Buick >> 2017 >> Envision Preferred, AWD >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System - Automatic >> Diagnostic Information and Procedures >> DTC B0223, B022A, B0233, B023A, B0408, B0418, B0428, or B3531: Recirculate Position Command/Air Flow Control/Air Flow Control/Temperature Control/Rear Air Flow Control >> Circuit/System Testing
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Circuit/System Testing

DTC B023A

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the components listed below. It may take up to 2 min for all vehicle systems to power down.
    • M37 Mode Door Actuator
    • M46 Air Recirculation Door Actuator
    • M6L Air Temperature Door Actuator - Left
    • M6R Air Temperature Door Actuator - Right
    • M37B Mode Door Actuator - Auxiliary (CJ4)
    • M6B Air Temperature Door Actuator - Auxiliary (CJ4)
  2. Disconnect the X3 and X4 harness connectors at the K33 HVAC Control Module.
  3. Test for infinite resistance between the K33 HVAC Control Module 12 V reference circuits listed below and ground:
    • K33 HVAC Control Module terminal 15 X3
    • K33 HVAC Control Module terminal 10 X4
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • If infinite resistance 
  4. Ignition ON.
  5. Test for less than 1 V between the K33 HVAC Control Module 12 V reference circuits listed below and ground:
    • K33 HVAC Control Module terminal 15 X3
    • K33 HVAC Control Module terminal 10 X4
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  6. Connect the X3 and X4 harness connectors at the K33 HVAC Control Module, ignition ON.
  7. Clear all DTCs.
  8. Verify DTC B023A is not set.
    • If the DTC is set. 

      Replace the K33 HVAC Control Module.

    • If the DTC is not set. 
  9. Verify DTC B023A does not set after connecting each of the components listed below one at a time and operating them through their full range.
    • M37 Mode Door Actuator
    • M46 Air Recirculation Door Actuator
    • M6L Air Temperature Door Actuator - Left
    • M6R Air Temperature Door Actuator - Right
    • M37B Mode Door Actuator - Auxiliary (CJ4)
    • M6B Air Temperature Door Actuator - Auxiliary (CJ4)
    • If the DTC sets 

      Replace the component that was connected immediately before the DTC set.

    • If the DTC does not set 
  10. All OK.

DTC B0223, B0233, B0408, B0418, B0428 or B3531

  1. Ignition OFF, disconnect the harness connector at the appropriate door actuator, It may take up to 2 min for all vehicle systems to power down. Ignition ON.
    2. NOTE:

    If more than one actuator is affected, test the B+ circuit at each actuator.

  2. Verify a test lamp illuminates between the 12 V reference circuit terminal 2 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.
    2. Test for infinite resistance between the 12 V reference circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the 12 V 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 K33 HVAC control module.
    • If the test lamp illuminates 
  3. Command the appropriate actuator with a scan tool.
  4. Verify a test lamp is flashing on and off when connected between the 12 V reference circuit terminal 2 and each control circuit terminal listed below:
    • Control Circuit - terminal 1
    • Control Circuit - terminal 3
    • Control Circuit - terminal 4
    • Control Circuit - terminal 6
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X3 harness connector at the K33 HVAC control module. Ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K33 HVAC Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC control module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K33 HVAC Control Module.
    • If the test lamp is flashing On and Off 
  5. Test or replace the actuator.
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