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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 162 (Data Communications - Diagnostic Information And Procedures (2 Of 3)) >> Diagnostic Information and Procedures >> DTC U1604 >> 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+, ignition, and serial data circuit terminals.

  1. Ignition ON/Vehicle In Service Mode.
  2. Verify the B218L Side Obstacle Detection Control Module - Left is not communicating.
    • If the device is still communicating 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the B218L Side Obstacle Detection Control Module - Left.
    2. Ignition ON/Vehicle In Service Mode, refer to step 7 to diagnose a fault in the serial data circuits.
    • Go to next step: If the device is not communicating 
  3. Ignition/Vehicle OFF, disconnect the harness connectors at the B218L Side Obstacle Detection Control Module - Left.
  4. Verify a test lamp illuminates between each of the ground circuit terminals 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 
  5. Ignition ON/Vehicle In Service Mode.
  6. If equipped, verify a test lamp illuminates between each of the B+ circuit terminals 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 B218L Side Obstacle Detection Control Module - Left.
    • Go to next step: If the test lamp illuminates 
  7. Test for less than 4.5 V between each of the private side obstacle detection CAN serial data circuit terminals and ground.
    • If 4.5 V or greater 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the B218R Side Obstacle Detection Control Module - Right.
    2. Ignition ON/Vehicle In Service Mode
    3. Test for less than 1 V between each of the private side obstacle detection CAN serial data circuit terminals and ground.
      • If 1 V or greater, repair the short to voltage in the serial data circuit.
      • Go to next step: If less than 1 V
    4. Replace the B218R Side Obstacle Detection Control Module - Right.
    • Go to next step: If less than 4.5 V 
  8. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
  9. Test for greater than 100 Ω between each of the private side obstacle detection CAN serial data circuit terminals and ground.
    • If 100 Ω or less 
    1. Disconnect the harness connectors at the B218R Side Obstacle Detection Control Module - Right.
    2. Test for infinite resistance between each of the private side obstacle detection CAN serial data circuit terminals and ground.
      • If less than infinite resistance, repair the short to ground in the serial data circuit.
      • Go to next step: If infinite resistance
    3. Replace the B218R Side Obstacle Detection Control Module - Right.
    • Go to next step: If greater than 100 Ω 
  10. Test for 110-130 Ω between each pair of the private side obstacle detection CAN serial data circuit terminals.
    • If less than 110 Ω 
    1. Disconnect the harness connectors at the B218R Side Obstacle Detection Control Module - Right.
    2. Test for infinite resistance between the pair of the private side obstacle detection CAN serial data circuit terminals.
      • If less than infinite resistance, repair the short together in the serial data circuit.
      • Go to next step: If infinite resistance
    3. Replace the B218R Side Obstacle Detection Control Module - Right.
    • If greater than 130 Ω 
    1. Disconnect the harness connectors at the B218R Side Obstacle Detection Control Module - Right.
    2. Test for less than 2 Ω in each of the private side obstacle detection CAN serial data circuits end to end between the B218L Side Obstacle Detection Control Module - Left and the B218R Side Obstacle Detection Control Module - Right.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 Ω
    3. Replace the B218R Side Obstacle Detection Control Module - Right.
    • Go to next step: If between 110-130 Ω 
  11. Inspect both harness and component connectors for contamination, corrosion, and terminal tension.
  12. Reconnect the harness connectors at the B218L Side Obstacle Detection Control Module - Left and the B218R Side Obstacle Detection Control Module - Right.
  13. Ignition ON/Vehicle In Service Mode.
  14. Verify the DTC is not set again.
    • If the DTC is set 

      Replace the B218L Side Obstacle Detection Control Module - Left.

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