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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 297 (Supplemental Restraints System) >> Diagnostic Information and Procedures >> DTC B10B4 or B120C >> 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.
NOTE:
  • Refer to SIR Service Precautions .
  • Refer to SIR Disabling and Enabling .
  • Inspect all terminals for damage or corrosion when disconnecting connectors. Damage or corrosion in the following requires repair or replacement of the affected component/connector.
    • Impact sensor
    • Restraints Control Module
    • Impact sensor wiring harness connector
    • Restraints Control Module wiring harness connector
  • The connector and connector position assurance (CPA) may seat independent of each other. Both the connector and CPA should seat with an audible and/or tactile click.
  1. Ignition OFF. It may take up to 2 min for all vehicle systems to power down.
  2. Verify the SIR system is disabled.
  3. Disconnect the harness connector at the appropriate B58 Front Impact Sensor.
  4. Test for less than 10 Ω between the low reference circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Disconnect the appropriate harness connector at the K36 Restraints Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K36 Restraints Control Module.
    • Go to next step: If less than 10 Ω 
  5. Test for greater than 50k Ω between the signal circuit terminal 1 and ground.
    • If 50k Ω or less 
    1. Test the following circuits for a short to ground.
      • DTC B10B4 = Circuit 354
      • DTC B120C = Circuit 1409
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K36 Restraints Control Module.
    • Go to next step: If greater than 50k Ω 
  6. Ignition ON,
  7. Verify the SIR system is disabled.
  8. Test for less than 1 V between the signal circuit terminal 1 and ground.
    • If 1 V or greater 
    1. Ignition OFF, disconnect the harness connector at the K36 Restraints Control Module, ignition ON.
    2. Test between the following circuits for short to voltage:
      • DTC B10B4 = Circuit 354, and Circuit 5045
      • DTC B120C = Circuit 1409, and Circuit 5600
      • If greater than 1 V, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K36 Restraints Control Module.
    • Go to next step: If less than 1 V 
    9. NOTE:

    When using the MIN MAX function, autorange on the DMM may not function properly. To ensure accurate test results, turn off autorange and manually set the DMM range to 000.0 V.

  9. Ignition OFF.
  10. Verify the SIR system is disabled.
  11. Install a DMM between the signal circuit terminal 1 and ground. Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V. Ignition ON.
  12. Verify the MAX voltage captured by the DMM is between 4 - 9V.
    • If less than 4 V 
    1. Verify the SIR system is disabled.
    2. Disconnect the appropriate harness connector at the K36 Restraints Control Module.
    3. Test between the following circuits for short to ground:
      • DTC B10B4 = Circuit 354, and Circuit 5045
      • DTC B120C = Circuit 1409, and Circuit 5600
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test the following circuits for open/high resistance:
      • DTC B10B4 = Circuit 354
      • DTC B120C = Circuit 1409
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the Restraints Control Module.
    • If greater than 9V 
    1. Ignition OFF. Disconnect the appropriate harness connector at the K36 Restraints Control Module. Ignition ON.
    2. Test for short to voltage between ground and the following circuits:
      • DTC B10B4 = Circuit 354
      • DTC B120C = Circuit 1409
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K36 Restraints Control Module.
    • Go to next step: If between 4 - 9V 
  13. Ignition OFF, connect all harness connectors, press in the CPA (if equipped) until an audible and/or tactile click is heard.
  14. Ignition ON, clear DTCs. Operate the vehicle within the Conditions for Running the DTC.
  15. Verify DTC B10B4 or B120C is not set.
    • If the DTC sets 
    1. Replace the B58 Front Impact Sensor.
    2. Verify the DTC does not set.
      • If the DTC sets, replace the K36 Restraints Control Module.
      • Go to next step: If the DTC does not set.
    3. All OK.
    • Go to next step: If the DTC does not set 
  16. A fault is not currently present and may be an intermittent condition.
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