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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 189 (Data Communications - Diagnostic Information And Procedures (1 Of 3)) >> Diagnostic Information and Procedures >> DTC U0212 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

Use the schematics and connector end views to identify the device's ground, B+, and LIN circuit terminals.

  1. Ignition/Vehicle OFF, disconnect all the harness connectors at the K99 Steering Column Control Module.
  2. Verify a test lamp illuminates between the ground circuit terminal and B+.
    • If the test lamp does not illuminate 

      Repair the open/high resistance in the ground circuit or ground connection.

    • Go to next step: If the test lamp illuminates 
  3. Ignition ON/Vehicle In Service Mode.
  4. If equipped, verify a test lamp illuminates between the B+ circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Test for an open/high resistance in the B+ circuit.
      • If an open/high resistance is found, repair the fault in the circuit.
      • Go to next step: If an open/high resistance is not found
    2. Verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Test for a short to ground in the B+ circuit.
      • If a short to ground is found, repair the fault in the circuit.
      • Go to next step: If a short to ground is not found
    2. Replace the K99 Steering Column Control Module.
    • Go to next step: If the test lamp illuminates 
    5. NOTE:

    For accurate voltage reading, disconnect the battery charger prior to performing the following test step.

  5. Test for 3.5 - 12 V between the Driver Seat Memory Control Module LIN Bus 1 circuit terminal and ground.
    • If less than 3.5 V 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the K40D Driver Seat Adjuster Memory Module.
    2. Test for infinite resistance between the LIN circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the LIN circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 Ω
    4. Replace the K40D Driver Seat Adjuster Memory Module.
    • If greater than 12 V 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the K40D Driver Seat Adjuster Memory Module.
    2. Ignition ON/Vehicle In Service Mode.
    3. Test for less than 1 V between the LIN circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    4. Replace the K40D Driver Seat Adjuster Memory Module.
    • Go to next step: If between 3.5 - 12 V 
  6. Inspect both harness and component connectors for contamination, corrosion, and terminal tension.
  7. Reconnect the harness connectors at the LIN device.
  8. Ignition ON/Vehicle In Service Mode.
  9. Verify DTC U0212 is not set again.
    • If the DTC is set 

      Replace the K99 Steering Column Control Module.

    • Go to next step: If the DTC is not set 
  10. A fault is currently not present and may be an intermittent condition.
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