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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 110 (Seat Heating And Cooling) >> Diagnostic Information and Procedures >> DTC B170C or B170E >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF and all vehicle systems OFF, disconnect the connector at the appropriate two seat blower motors listed below:
    • DTC B170C = M73A Front Seat Back Ventilation Blower - Driver and M73D Front Seat Cushion Ventilation Blower - Driver
    • DTC B170E = M73B Front Seat Back Ventilation Blower - Passenger and M73P Front Seat Cushion Ventilation Blower - Passenger
  2. Verify a test lamp illuminates between the appropriate ground circuit terminals listed below and B+, one at a time.
    • DTC B170C = Terminal 3 at M73A Front Seat Back Ventilation Blower - Driver
    • DTC B170C = Terminal 3 at M73D Front Seat Cushion Ventilation Blower - Driver
    • DTC B170E = Terminal 3 at M73B Front Seat Back Ventilation Blower - Passenger
    • DTC B170E = Terminal 3 at M73P Front Seat Cushion Ventilation Blower - Passenger
    • If the test lamp does not illuminate 
    1. Test the appropriate circuit for an open/high resistance:
      • Terminal 3 at M73A Front Seat Back Ventilation Blower - Driver = Circuit 2150
      • Terminal 3 at M73D Front Seat Cushion Ventilation Blower - Driver = Circuit 2150
      • Terminal 3 at M73B Front Seat Back Ventilation Blower - Passenger = Circuit 2250
      • Terminal 3 at M73P Front Seat Cushion Ventilation Blower - Passenger = Circuit 2250
    • Go to next step: If the test lamp illuminates 
  3. Verify a test lamp illuminates between the appropriate B+ circuit terminals listed below and ground, one at a time.
    • DTC B170C = Terminal 1 at M73A Front Seat Back Ventilation Blower - Driver
    • DTC B170C = Terminal 1 at M73D Front Seat Cushion Ventilation Blower - Driver
    • DTC B170E = Terminal 1 at M73B Front Seat Back Ventilation Blower - Passenger
    • DTC B170E = Terminal 1 at M73P Front Seat Cushion Ventilation Blower - Passenger
    • If the test lamp does not illuminate and the circuit fuse is good 

      Repair the open/high resistance on the circuit 539.

    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Test the circuit 539 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found
    2. Replace the appropriate M73 Seat Blower Motor.
    • Go to next step: If the test lamp illuminates 
  4. Connect a test lamp between the two appropriate control circuit terminal and B+, one at a time.
    • DTC B170C = Terminal 2 at M73A Front Seat Back Ventilation Blower - Driver
    • DTC B170C = Terminal 2 at M73D Front Seat Cushion Ventilation Blower - Driver
    • DTC B170E = Terminal 2 at M73B Front Seat Back Ventilation Blower - Passenger
    • DTC B170E = Terminal 2 at M73P Front Seat Cushion Ventilation Blower - Passenger
  5. Ignition ON, Verify the test lamp turns ON when pressing the vented seat switch through the High, Medium, and Low positions and the test lamp turns OFF when the OFF position is reached.
    • If the test lamp does not turn ON 
    1. Test the appropriate circuit for a short to voltage:
      • DTC B170C = Circuit 5906
      • DTC B170E = Circuit 5908
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found
    2. Test the appropriate circuit for an open/high resistance:
      • DTC B170C = Circuit 5906
      • DTC B170E = Circuit 5908
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found
    3. Replace the K29F Front Seat Heater Control Module.
    • If the test lamp does not turn OFF 
    1. Test the appropriate circuit for a short to ground:
      • DTC B170C = Circuit 5906
      • DTC B170E = Circuit 5908
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found
    2. Replace the K29F Front Seat Heater Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  6. Ignition OFF, connect the appropriate component listed below:
    • DTC B170C = M73D Front Seat Cushion Ventilation Blower - Driver
    • DTC B170E = M73P Front Seat Cushion Ventilation Blower - Passenger
  7. Clear the DTC.
  8. Ignition ON, operate the appropriate vented seat switch through the High, Medium, and Low positions and verify a DTC does not set.
    • DTC B170C = Driver Vented Seat
    • DTC B170E = Passenger Vented Seat
    • If a DTC sets 
    1. Replace the appropriate component listed below:
      • DTC B170C = M73D Front Seat Cushion Ventilation Blower - Driver
      • DTC B170E = M73P Front Seat Cushion Ventilation Blower - Passenger
    • Go to next step: If no DTC sets 
  9. Replace the appropriate component listed below:
    • DTC B170C = M73A Front Seat Back Ventilation Blower - Driver
    • DTC B170E = M73B Front Seat Back Ventilation Blower - Passenger
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