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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Wiring Systems And Power Management - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B1A76 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition Off, disconnect the S38 On/Off Vehicle Switch.
  2. Verify a test lamp illuminates between the low reference circuit terminal 7 and B+.
    • If the test lamp does not illuminate 
    1. Disconnect the X2 connector at the K56 Serial Data Gateway Module.
    2. Test the low reference circuit 3559 for an open/high resistance condition.
      • If an open/high resistance condition is found, repair the open/high resistance in the circuit.
      • Go to next step: If an open/high resistance condition is not found
    3. Replace the K56 Serial Data Gateway Module.
    • Go to next step: If the test lamp illuminates 
  3. Connect the S38 On/Off Vehicle Switch.
  4. Ignition On Vehicle in Run mode.
  5. Disconnect the S38 On/Off Vehicle Switch
  6. Test for between 4.7 v and 5.3 v between the signal circuit terminal 8 and ground.
    • If not the specified value 
    1. Disconnect the X2 connector at the K56 Serial Data Gateway Module.
    2. Test the signal circuit 3558 for short to ground condition.
      • If a short to ground condition is found, repair the short to ground in the circuit.
      • Go to next step: If a short to ground condition is not found
    3. Test the signal circuit 3558 for an open/high resistance condition.
      • If an open/high resistance condition is found, repair the open/high resistance in the circuit.
      • Go to next step: If an open/high resistance condition is not found
    4. Test for greater than 5.9 v on the signal circuit 3558.
      • If greater than 5.9 V is found, repair the short to voltage in the circuit.
      • Go to next step: If greater than 5.9 v is not found
    5. Replace the K56 Serial Data Gateway Module.
    • Go to next step: If the Specified Value 
  7. Connect the S38 On/Off Vehicle Switch.
  8. Ignition Off Vehicle Off Power Mode.
  9. Disconnect the connector at the S38 On/Off Vehicle Switch.
  10. Test for 6.0k-7.5K Ω between Signal terminal 8 and low reference terminal 7 with the S38 On/Off Vehicle Switch not pressed.
    • If not between 6.0k-7.5K Ω 

      Replace the S38 On/Off Vehicle Switch.

    • Go to next step: If between 6.0k-7.5K Ω 
  11. Test for 1.3k-1.8k Ω between Signal terminal 8 and low reference terminal 7 with the S38 On/Off Vehicle Switch pressed.
    • If not between 1.3k-1.8k Ω 

      Replace the S38 On/Off Vehicle Switch.

    • Go to next step: If between 1.3k-1.8k Ω 
  12. Replace the K56 Serial Data Gateway Module.
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