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Home >> Cadillac >> 2019 >> XT5 Base, FWD >> Repair and Diagnosis >> Accessories & Equipment >> Anti-Theft Systems >> Keyless Entry System And Remote Functions >> Diagnostic Information and Procedures >> DTC B3122 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the T10J Keyless Entry Antenna - Center Console Front, ignition ON.
  2. 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 K84 Keyless Entry Control Module, ignition 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 K84 Keyless Entry Control Module.
    • Go to next step: If less than 1 V 
    3. 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 0 - 400/600 V.

  3. Ignition OFF, install a DMM between the signal circuit terminal 1 and ground. Set the DMM to capture DC voltage using the PEAK MIN MAX function. Turn off autorange and manually set the DMM range to 0 - 400/600 V.
  4. Activate the antenna by pressing the ignition mode switch.
  5. Verify the MAX voltage captured by the DMM is greater than 1 V.
    • If 1 V or less 
    1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module.
    2. Test for infinite resistance between the signal 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 signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K84 Keyless Entry Control Module.
    • Go to next step: If greater than 1 V 
  6. Test for less than 1 V between the low reference circuit terminal 2 and ground.
    • If 1 V or greater 
    1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module, ignition ON.
    2. Test for less than 1 V between the low reference circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K84 Keyless Entry Control Module.
    • Go to next step: If less than 1 V 
    7. 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 0 - 400/600 V.

  7. Install a DMM between the signal circuit terminal 1 and the low reference circuit terminal 2. Set the DMM to capture DC voltage using the PEAK MIN MAX function. Turn off autorange and manually set the DMM range to 0 - 400/600 V.
  8. Activate the antenna by pressing the ignition mode switch.
  9. Verify the MAX voltage captured by the DMM is greater than 1 V.
    • If 1 V or less 
    1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module.
    2. Test for infinite resistance between the low reference 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 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 K84 Keyless Entry Control Module.
    • Go to next step: If greater than 1 V 
  10. Replace the T10J Keyless Entry Antenna - Center Console Front.
  11. Activate the antenna by pressing the ignition mode switch.
  12. Verify DTC B3122 is not set.
    • If DTC B3122 is set 

      Replace the K84 Keyless Entry Control Module.

    • Go to next step: If DTC B3122 is not set 
  13. All OK.
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