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Home >> Chevrolet >> 2020 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 44 (Lighting System - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B3948 or B3949 >> Circuit/System Testing

Circuit/System Testing

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DTC B3948

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector:X5 @ K9 Body Control Module
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points:
    • Terminal 3 @ Control module harness & Ground
    • Terminal 4 @ Control module harness & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:X1 @ X50A Fuse Block - Underhood
    3. Test for less than 2 ohms between the test points:

      Terminal 3 @ Control module harness & Terminal J4 @ Component harness

      Terminal 4 @ Control module harness & Terminal H4 @ Component harness

      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector:X1 @ X50A Fuse Block - Underhood
    3. Test for infinite resistance between the test points:

      Terminal J4 @ Component harness & Ground

      Terminal H4 @ Component harness & Ground

      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component:K9 Body Control Module
    • Go to next step: If the test lamp turns On 
  5. Ignition/Vehicle & All vehicle systems - Off
  6. Connect the electrical connector:X5 @ K9 Body Control Module
  7. Disconnect the appropriate electrical connector:
    • E4LF Turn Signal Lamp - Left Front
    • { DWN/DWS } A9A Outside Rearview Mirror - Driver - X510
    8. 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.

  8. Test for less than 15 ohms between the test points:
    • Terminal B @ E4LF Turn Signal Lamp - Left Front & Ground
    • { DWN/DWS } Terminal 5 @ A9A Outside Rearview Mirror - Driver - X510 & Ground
    • If 15 ohms or greater 
    1. Ignition/Vehicle - Off
    2. Test for less than 2 ohms between the test points:

      Terminal B @ E4LF Turn Signal Lamp - Left Front & Ground terminal

      { DWN/DWS } Terminal 5 @ A9A Outside Rearview Mirror - Driver - X510 & Ground terminal (DWN/DWS)

      • 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 15 ohms 
  9. Connect a test lamp between the test points:
    • Terminal AE4LF Turn Signal Lamp - Left Front @ & Ground
    • { DWN/DWS } Terminal 13 @ & A9A Outside Rearview Mirror - Driver - X510Ground
  10. Ignition - On / Vehicle - In Service Mode
  11. Perform the scan tool control function:Left Front Turn Signal Circuit - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector:X5 @ K9 Body Control Module
    3. Test for infinite resistance between the test points:Control circuit terminal 2 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points:

      Control circuit terminal 2 @ Control module harness & Terminal A @ E4LF Turn Signal Lamp - Left Front

      { DWN/DWS } Control circuit terminal 2 @ Control module harness & Terminal 13 @ A9A Outside Rearview Mirror - DriverX510

      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K9 Body Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector:X5 @ K9 Body Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 2 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component:K9 Body Control Module
    • Go to next step: If the test lamp turns On and Off 
  12. Test or replace the component:E4LF Turn Signal Lamp - Left Front

DTC B3949

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector:X1 @ K9 Body Control Module
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points:B+ circuit terminal 3 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off
    2. Remove the component:F8DA @ X51A Fuse Block - Instrument Panel
    3. Test for less than 2 ohms between the test points:B+ circuit terminal 3 @ Control module harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off
    2. Remove the component:F8DA @ X51A Fuse Block - Instrument Panel
    3. Test for infinite resistance between the test points:B+ circuit terminal 3Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component:K9 Body Control Module
    • Go to next step: If the test lamp turns On 
  5. Ignition/Vehicle & All vehicle systems - Off
  6. Connect the electrical connector:X1 @ K9 Body Control Module
  7. Disconnect the appropriate electrical connector:
    • E4RF Turn Signal Lamp - Right Front
    • { DWN/DWS } A9B Outside Rearview Mirror - Passenger - X610
    8. 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.

  8. Test for less than 15 ohms between the test points:
    • Terminal B @ E4RF Turn Signal Lamp - Right Front & Ground
    • { DWN/DWS } Terminal 5 @ A9B Outside Rearview Mirror - Passenger - X610 & Ground
    • If 15 ohms or greater 
    1. Ignition/Vehicle - Off
    2. Test for less than 2 ohms between the test points:

      Terminal B @ E4RF Turn Signal Lamp - Right Front & Ground terminal

      { DWN/DWS } Terminal 5 @ A9B Outside Rearview Mirror - Passenger - X610 & Ground terminal

      • 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 15 ohms 
  9. Connect a test lamp between the test points:
    • Terminal A @ E4RF Turn Signal Lamp - Right Front & Ground
    • { DWN/DWS } Terminal 13 @ A9B Outside Rearview Mirror - Passenger - X610 & Ground (DWN/DWS)
  10. Ignition - On / Vehicle - In Service Mode
  11. Perform the scan tool control function:Right Front Turn Signal Circuit - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector:X4 @ K9 Body Control Module
    3. Test for infinite resistance between the test points:

      Terminal A @ E4RF Turn Signal Lamp - Right Front & Ground

      { DWN/DWS } Terminal 13 @ A9B Outside Rearview Mirror - Passenger - X610 & Ground

      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points:

      Terminal A @ E4RF Turn Signal Lamp - Right Front & Terminal 3 @ Control module harness

      { DWN/DWS } Terminal 13 @ A9B Outside Rearview Mirror - Passenger - X610 & Terminal 3 @ Control module harness

      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K9 Body Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector:X4 @ K9 Body Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:

      Terminal 3 @ Control module harness & Ground

      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component:K9 Body Control Module
    • Go to next step: If the test lamp turns On and Off 
  12. Test or replace the component:E4RF Turn Signal Lamp - Right Front
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