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
   • M4 Air Inlet Door Actuator
   • M6 Air Temperature Door Actuator
2. Disconnect the harness connector at the K33 HVAC Control Module.
3. Test for infinite resistance between the K33 HVAC Control Module 12 V reference circuit terminal 15 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 12 V reference circuit terminal 15 and ground.
   • If 1 V or greater 

     Repair the short to voltage on the circuit.

   • If less than 1 V 
6. Connect the harness connector 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
   • M4 Air Inlet Door Actuator
   • M6 Air Temperature Door Actuator
   • If the DTC sets after connecting one of the components 

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

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

DTC B0223, B0233, or B0408

1. Ignition OFF, disconnect the harness connector at the appropriate door actuator and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground.
   • If the test lamp does not illuminate 
   1. Disconnect the X3 harness connector at the K33 HVAC Control Module.
   2. Test for infinite resistance between the B+ 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 B+ 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. Test for less than 1 V between ground and the control circuits listed below:
   • Control Circuit - terminal 1
   • Control Circuit - terminal 3
   • Control Circuit - terminal 4
   • Control Circuit - terminal 6
   • If 1 V or greater 

     Repair the short to voltage on the circuit.

   • If less than 1 V 
4. Ignition OFF.
5. Test for infinite resistance between ground and the control circuits listed below:
   • Control Circuit - terminal 1
   • Control Circuit - terminal 3
   • Control Circuit - terminal 4
   • Control Circuit - terminal 6
   • If less than infinite resistance 

     Repair the short to ground on the circuit.

   • If infinite resistance 
6. Disconnect the X3 harness connector at the K33 HVAC Control Module.
7. Test for less than 2 Ω end to end in the circuits listed below:
   • Control Circuit - terminal 1
   • Control Circuit - terminal 3
   • Control Circuit - terminal 4
   • Control Circuit - terminal 6
   • B+ Circuit - terminal 2
   • If 2 Ω or greater 

     Repair the open/high resistance in the circuit.

   • If less than 2 Ω 
NOTE:

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

8. Test or replace the actuator.
9. Verify the symptom or DTC was corrected.
   • If the symptom or DTC was not corrected 

     Replace the K33 HVAC Control Module.

   • If the symptom or DTC was corrected 
10. All OK.