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Home >> Cadillac >> 2019 >> CTS Base, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 90 (Power Door Lock System And Release Systems) >> Diagnostic Information and Procedures >> DTC B3938 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2018 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: M97 Fuel Fill Door Lock Actuator
  3. Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2
  4. Ignition - On/Vehicle - In Service Mode
  5. Operate the component: S13D Door Lock Switch - Driver - Lock & Unlock
  6. Verify the test lamp does not turn On and Off.
    • If the test lamp turns On and Off 

      Test or replace the component: M97 Fuel Fill Door Lock Actuator

    • Go to next step: If the test lamp does not turn On and Off 
  7. Disconnect the electrical connector: X6 @ K9 Body Control Module
  8. Disconnect the electrical connector: X3 @ X53A Fuse Block - Rear Body
  9. Test for less than 2 ohms between the test points:
    • Control circuit terminal 1 @ Component harness & Terminal 4 X6 @ Control module harness
    • Control circuit terminal 2 @ Component harness & Terminal 19 X3 @ Fuse Block Harness
    • If 2 ohms or greater - Repair the open/high resistance in the circuit.
    • Go to next step: If less than 2 ohms 
  10. NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  11. Ignition/Vehicle & All vehicle systems - Off
  12. Connect the electrical connector: X6 @ K9 Body Control Module
  13. Connect the electrical connector: X3 @ X53A Fuse Block - Rear Body
  14. Disconnect the electrical connector: X2 @ X53A Fuse Block - Rear Body
  15. Test for less than 10 ohms between the test points: Ground circuit terminal 27 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 27 & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  16. Connect the electrical connector: X2 @ X53A Fuse Block - Rear Body
  17. Disconnect the electrical connector: X7 @ K9 Body Control Module
  18. Ignition - On/Vehicle - In Service Mode
  19. Momentarily connect a 3 A fused jumper wire between the test points: Control circuit terminal 4 X7 & B+

    Verify the component produces a clicking sound: KR132 Fuel Fill Door Lock Relay

    • If the component does not produce a sound 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: X2 @ X53A Fuse Block - Rear Body
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 4 X7 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for infinite resistance between the test points: Control circuit terminal 4 X7 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    7. Test for less than 2 ohms between the test points: Control circuit terminal 4 X7 @ Control module harness & Control circuit terminal 31 X2 @ Fuse Block Harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component: X53A Fuse Block - Rear Body
    • Go to next step: If the component turns On and Off 
  20. Replace the component: K9 Body Control Module