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Home >> GMC >> 2019 >> Terrain SL >> Repair and Diagnosis >> External Pages >> Different car >> Section 630 (Keyless Entry System And Remote Functions) >> Diagnostic Information and Procedures >> DTC B1442 >> 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:

Verify the antenna is installed correctly and not damaged.

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR76 Retained Accessory Power Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  3. Verify the test lamp turns ON and OFF when commanding the Interruptible Retained Accessory Power Relay On and Off with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control 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 control 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 is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control 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.
    • Go to next step: If the test lamp turns ON and OFF 
  4. Verify that a test lamp does not illuminate between the ignition circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the ignition circuit

    • Go to next step: If the test lamp does not illuminate 
  5. Ignition ON, connect a 40 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
  6. Verify device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    2. Test for infinite resistance between the ignition 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 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 device.
    • Go to next step: If the device activates 
  7. Test or replace the KR76 Retained Accessory Power Relay.
  8. Ignition OFF and all vehicle systems OFF, disconnect the KR73 Ignition Main Relay. It may take up to 2 min for all vehicle systems to power down.
  9. Test for less than 10 Ω between the ground circuit terminal 86 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 Ω 
  10. Ignition ON.
  11. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate 

      Replace the X50A Fuse Block - Underhood

    • Go to next step: If the test lamp illuminates 
  12. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
  13. Verify the test lamp turns ON and OFF when commanding the Run/Crank Relay On and Off with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control 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 control 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 is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control 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.
    • Go to next step: If the test lamp turns ON and OFF 
  14. Verify that a test lamp does not illuminate between the ignition circuits listed below and ground.
    • Ignition circuit terminal 87
    • Ignition circuit terminal 87A
    • If the test lamp illuminates 

      Repair the short to voltage on the ignition circuit.

    • Go to next step: If the test lamp does not illuminate 
  15. Ignition ON, connect a 40 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuits listed below.
    • Ignition circuit terminal 87
    • Ignition circuit terminal 87A
  16. Verify device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    2. Test for infinite resistance between the ignition 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 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 device.
    • Go to next step: If the device activates 
  17. Test or replace the KR73 Ignition Main Relay.
  18. Ignition OFF, disconnect the harness connector at the T10U Low Frequency Instrument Panel Antenna, ignition ON.
  19. 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 K9 Body 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 K9 Body Control Module.
    • Go to next step: If less than 1 V 
    20. 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.

  20. Ignition OFF, 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.
  21. Activate the antenna by pressing the Stop/Start switch.
  22. 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 K9 Body 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 K9 Body Control Module.
    • Go to next step: If greater than 1 V 
  23. 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 K9 Body 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 K9 Body Control Module.
    • Go to next step: If less than 1 V 
    24. 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.

  24. 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 MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V.
  25. Activate the antenna by pressing the Stop/Start switch.
  26. 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 K9 Body 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 K9 Body Control Module.
    • Go to next step: If greater than 1 V 
  27. Replace the T10U Low Frequency Instrument Panel Antenna.
  28. Activate the antenna by pressing the Stop/Start switch a minimum of three times to meet the conditions for setting the DTC.
  29. Verify DTC B1442 is not set.
    • If DTC B1442 is set 

      Replace the K9 Body Control Module.

    • Go to next step: If DTC B1442 is not set 
  30. All OK.
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