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Home >> Buick >> 2015 >> Regal GS, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting System - Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC B3883: License Plate Lamp >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the X2 harness connector at the K9 body Control Module, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2Ω in the B+ circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K9 body Control Module.
    • If the test lamp illuminates 
  3. Ignition OFF, connect the X2 harness connector at the K9 body Control Module.
  4. Ignition OFF, exterior lamps OFF, trunk latch latched, remove both E7 License Plate Lamp bulbs.
  5. Test for less than 5Ω between each ground circuit terminal 2 and ground.
    • If 5Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2Ω in the ground circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, repair the open/high resistance in the ground connection.
    • If less than 5Ω 
  6. Connect a test lamp between the E7 License Plate Lamp - Left control circuit terminal 1 and ground, ignition ON.
  7. Verify the test lamp turns ON and OFF when commanding the License Plate Lamps ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X4 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.
      • If infinite resistance
    3. Test for less than 2Ω in the control circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the K9 body Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X4 harness connector at the K9 body Control Module, ignition ON.
    2. Test for less than 1V between the control circuit terminal and ground.
      • If 1V or greater, repair the short to voltage on the circuit.
      • If less than 1V, replace the K9 body Control Module.
    • If the test lamp turns ON and OFF 
  8. Ignition OFF.
  9. Connect a test lamp between the E7R License Plate Lamp - Right control circuit terminal 1 and ground, ignition ON.
  10. Verify the test lamp turns ON and OFF when commanding the License Plate Lamps ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X4 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.
      • If infinite resistance
    3. Test for less than 2Ω in the control circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
    • If the test lamp turns ON and OFF 
  11. Test or replace the E7 License Plate Lamp.
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