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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 376 (Seat Heating System And Seat Cooling System) >> Diagnostic Information and Procedures >> DTC B12CC, B1338, B1339, or B133A >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.

B12CC or B1338

    NOTE:

    Circuit/System Verification must be performed before proceeding with Circuit/System Testing

  1. Ignition OFF, disconnect the connector at each component listed below. It may take up to 2 min for all vehicle systems to power down.
    • E14A Front Seat Back Heater - Driver
    • E14B Front Seat Cushion Heater - Driver
  2. Test for less than 40 Ω between each low reference circuit terminal listed below and ground, one at a time.
    • Terminal 3 at E14A Front Seat Back Heater - Driver
    • Terminal 3 at E14B Front Seat Cushion Heater - Driver
    • If 40 Ω or greater 
    1. Test circuit 2080 for an open/high resistance.
      • 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
    2. Replace the K29F Front Seat Heater Control Module.
    • Go to next step: If less than 40 Ω 
  3. Ignition ON.
  4. Test for 4.8 - 5.2 V between each signal circuit terminal listed below and ground, one at a time.
    • Terminal 2 at E14A Front Seat Back Heater - Driver
    • Terminal 2 at E14B Front Seat Cushion Heater - Driver
    • If less than 4.8 V 
    1. Test the appropriate circuit for a short to ground:
      • Terminal 2 at E14A Front Seat Back Heater - Driver = Circuit 2425
      • Terminal 2 at E14B Front Seat Cushion Heater - Driver = Circuit 2079
      • 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. Test the appropriate circuit for an open/high resistance:
      • Terminal 2 at E14A Front Seat Back Heater - Driver = Circuit 2425
      • Terminal 2 at E14B Front Seat Cushion Heater - Driver = Circuit 2079
      • 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 greater than 5.2 V 
    1. Test the appropriate circuit for a short to voltage:
      • Terminal 2 at E14A Front Seat Back Heater - Driver = Circuit 2425
      • Terminal 2 at E14B Front Seat Cushion Heater - Driver = Circuit 2079
      • 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. Replace the K29F Front Seat Heater Control Module.
    • Go to next step: If between 4.8 - 5.2 V 
  5. Ignition OFF, connect the connectors at the E14B Front Seat Cushion Heater - Driver and the E14A Front Seat Back Heater - Driver. Disconnect the X2 connector at the K29F Front Seat Heater Control Module.
  6. Test for 500 Ω - 300 kΩ between the signal circuit and the low reference circuit terminals listed below, one at a time.
    • Terminal 3 and terminal 1 at K29F Front Seat Heater Control Module
    • Terminal 6 and terminal 1 at K29F Front Seat Heater Control Module
    • If not between 500 Ω - 300 kΩ 
    1. Replace the appropriate component:
      • Terminal 3 and terminal 1 at K29F Front Seat Heater Control Module = E14A Front Seat Back Heater - Driver
      • Terminal 6 and terminal 1 at K29F Front Seat Heater Control Module = E14B Front Seat Cushion Heater - Driver
    • Go to next step: If between 500 Ω - 300 kΩ 
  7. Replace the K29F Front Seat Heater Vent Control Module.

B1339 or B133A

    NOTE:

    Circuit/System Verification must be performed before proceeding with Circuit/System Testing

  1. Ignition OFF, disconnect the connector at each component listed below. It may take up to 2 min for all vehicle systems to power down.
    • E14C Front Seat Back Heater - Passenger
    • E14D Front Seat Cushion Heater - Passenger
  2. Test for less than 40 Ω between each low reference circuit terminal listed below and ground, one at a time.
    • Terminal 3 at E14C Front Seat Back Heater - Passenger
    • Terminal 3 at E14D Front Seat Cushion Heater - Passenger
    • If 40 Ω or greater 
    1. Test the appropriate circuit for an open/high resistance:
      • Terminal 3 at E14C Front Seat Back Heater - Passenger = Circuit 2482
      • Terminal 3 at E14D Front Seat Cushion Heater - Passenger = Circuit 2435
      • 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
    2. Replace the K29F Front Seat Heater Control Module.
    • Go to next step: If less than 40 Ω 
  3. Ignition ON.
  4. Test for 4.8 - 5.2 V between each signal circuit terminal listed below and ground, one at a time.
    • Terminal 2 at E14C Front Seat Back Heater - Passenger
    • Terminal 2 at E14D Front Seat Cushion Heater - Passenger
    • If less than 4.8 V 
    1. Test the appropriate circuit for a short to ground:
      • Terminal 2 at E14C Front Seat Back Heater - Passenger = Circuit 2436
      • Terminal 2 at E14D Front Seat Cushion Heater - Passenger = Circuit 2434
      • 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. Test the appropriate circuit for an open/high resistance:
      • Terminal 2 at E14C Front Seat Back Heater - Passenger = Circuit 2436
      • Terminal 2 at E14D Front Seat Cushion Heater - Passenger = Circuit 2434
      • 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 greater than 5.2 V 
    1. Test the appropriate circuit for a short to voltage:
      • Terminal 2 at E14C Front Seat Back Heater - Passenger = Circuit 2436
      • Terminal 2 at E14D Front Seat Cushion Heater - Passenger = Circuit 2434
      • 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. Replace the K29F Front Seat Heater Control Module.
    • Go to next step: If between 4.8 - 5.2 V 
  5. Ignition OFF, connect the connectors at the E14D Front Seat Cushion Heater - Passenger and the E14C Front Seat Back Heater - Passenger. Disconnect the X2 connector at the K29F Front Seat Heater Control Module.
  6. Test for 500 Ω - 300 kΩ between the signal circuit and the low reference circuit terminals listed below, one at a time.
    • Terminal 4 and terminal 12 at K29F Front Seat Heater Control Module
    • Terminal 5 and terminal 2 at K29F Front Seat Heater Control Module
    • If not between 500 Ω - 300 kΩ 
    1. Replace the appropriate component:
      • Terminal 4 and terminal 12 at K29F Front Seat Heater Control Module = E14C Front Seat Back Heater - Passenger
      • Terminal 5 and terminal 2 at K29F Front Seat Heater Control Module = E14D Front Seat Cushion Heater - Passenger
    • Go to next step: If between 500 Ω - 300 kΩ 
  7. Replace the K29F Front Seat Heater Control Module.
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