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Home >> Cadillac >> 2016 >> ELR >> Repair and Diagnosis (Single Page) >> Body & Frame >> Ignition Switch/Steering Lock >> Immobilizer System >> Diagnostic Information and Procedures >> DTC B2955: Security Sensor Data Circuit Malfunction >> Circuit/System Testing
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Circuit/System Testing

  1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the K89 Immobilizer Control Module. It may take up to 2 min for all vehicle systems to power down.
  2. Verify a test lamp illuminates between the low reference circuit terminal 1 and B+.
    • If the test lamp does not illuminate 
    1. Vehicle OFF, disconnect the harness connector at the K9 Body 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 K9 Body Control Module.
    • If the test lamp illuminates 
  3. Vehicle in Service Mode.
    4. NOTE:

    In some instances, the K9 Body Control Module may only apply voltage for 3 s immediately after the ignition mode switch is pressed. It may be necessary to monitor the DMM while pressing the ignition mode switch to observe the voltage.

  4. Test for greater than 9 V between the ignition circuit terminal 3 and ground.
    • If 9 V or less 
    1. Vehicle OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If greater than 9 V 
  5. Vehicle in Service Mode.
  6. Test for 12-13 V between the serial data circuit terminal 2 and ground.
    • If less than 12 V 
    1. Vehicle OFF, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the serial data circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the serial data circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • If greater than 13 V 
    1. Vehicle OFF, disconnect the harness connector at the K9 Body Control Module, vehicle ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If within 12-13 V 
  7. Replace the K89 Immobilizer Control Module.
  8. Verify DTC B2955 is not set.
    • If DTC B2955 is set 

      Replace the K9 Body Control Module.

    • If DTC B2955 is not set or is set as history 
  9. All OK.
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