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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 238 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> DTC B0223, B0228, B0233, B0408, B0413, B0418, B0423, B1395, or B374A: Recirculation/Main Temperature Control >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1395

  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
  2. Disconnect the harness connectors at the K33 HVAC Control Module.
  3. Test for infinite resistance between the K33 HVAC Control Module 5 V reference circuit terminal 17 X2 and ground.
    • 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 5 V reference terminal 17 X2 and ground.
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  6. Clear all DTCs.
  7. Ignition OFF, connect the harness connectors at the K33 HVAC Control Module, ignition ON.
  8. Verify DTC B1395 is not set.
    • If the DTC is set. 

      Replace the K33 HVAC Control Module.

    • If the DTC is not set. 
  9. Verify DTC B1395 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
    • If the DTC sets after connecting one of the components 

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

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

DTC B0223, B0228, B0233, B0408, B0413, B0418, B0423, or B374A

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

    The scan tool must be disconnected from the vehicle before performing the next test.

  2. Test for less than 10 Ω between ground and the low reference circuit terminal of the appropriate actuator below:
    • M37 Mode Door Actuator terminal 2
    • M46 Air Recirculation Door Actuator terminal 1
    • M6L Air Temperature Door Actuator - Left terminal 2
    • M6R Air Temperature Door Actuator - Right terminal 2
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connectors at the K33 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 K33 HVAC Control Module.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Test for 4.8-5.2 V between ground and the 5 V reference circuit terminal of the appropriate actuator listed below:
    • M37 Mode Door Actuator terminal 1
    • M46 Air Recirculation Door Actuator terminal 2
    • M6L Air Temperature Door Actuator - Left terminal 1
    • M6R Air Temperature Door Actuator - Right terminal 1
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module.
    2. Test for infinite resistance between the 5 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 5 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 greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the 5 V reference circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K33 HVAC Control Module.
    • If between 4.8-5.2 V 
  5. Test for 4.8-5.2 V between the signal circuit terminal 3 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module.
    2. Test for infinite resistance between the signal 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 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 K33 HVAC Control Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K33 HVAC Control Module.
    • If between 4.8-5.2 V 
  6. Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
  7. Test for less than 1 V between each control circuit listed below and ground:
    • Actuator terminal 4
    • Actuator terminal 5
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  8. Ignition OFF.
  9. Test for infinite resistance between each control circuit listed below and ground:
    • Actuator terminal 4
    • Actuator terminal 5
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • If infinite resistance 
  10. Test for less than 2 Ω in each control circuit end to end.
    • If 2 Ω or greater 

      Repair the open/high resistance in the circuit.

    • If less than 2 Ω 
    11. NOTE:

    Before replacing an actuator, verify that there are no mechanical issues with the air control door and any associated components.

  11. Test or replace the actuator.
  12. Verify the DTC or symptom is corrected while operating the HVAC system under the Conditions for Running the DTC.
    • If the DTC or symptom is not corrected 

      Replace the K33 HVAC Control Module.

    • If the DTC or symptom is corrected 
  13. All OK.
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