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Home >> Cadillac >> 2018 >> XT5 Platinum >> Repair and Diagnosis >> Accessories & Equipment >> Headlights >> Lighting System - Diagnostic Information And Procedures (DTC B3950 - C0297) >> Diagnostic Information and Procedures >> Courtesy Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

    NOTE:

    Each lighting component may need to be disconnected to isolate a short to ground. Use the wiring schematics to identify the following:

    • Lighting components the vehicle is equipped with
    • Each component's control and ground circuit terminals
    • Component locations on the lighting control circuit
  1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the F1DA fuse at the X51A Fuse Block - Instrument Panel.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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, remove the F1DA fuse at the X51A Fuse Block - Instrument Panel.
    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.
    • Go to next step: If the test lamp illuminates 
  3. Ignition OFF, connect the X5 harness connector at the K9 Body Control Module.
  4. Disconnect the harness connector at the A98 Front Overhead Console Assembly, ignition ON.
  5. 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, remove the F57RA fuse at the X51A Fuse Block - Rear Body.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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, remove the F57RA fuse at the X51A Fuse Block - Rear Body.
    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 A98 Front Overhead Console Assembly.
    • Go to next step: If the test lamp illuminates 
  6. Ignition OFF, connect the harness connector at the A98 Front Overhead Console Assembly.
  7. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, open and close drivers door, disconnect the harness connector at the inoperative courtesy lamp. It may take up to 2 min for all vehicle systems to power down.
  8. Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
    • A3L Sunshade - Left terminal B
    • A3R Sunshade - Right terminal B
    • A98 Front Overhead Console Assembly terminal 5
    • E27 Instrument Panel Compartment Lamp terminal 2
    • E37LR Dome/Reading Lamps - Left Rear terminal 3
    • E37RR Dome/Reading Lamps - Right Rear terminal 3
    • 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 
  9. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
    • A3L Sunshade - Left terminal A
    • A3R Sunshade - Right terminal A
    • A98 Front Overhead Console Assembly terminal 7
    • E27 Instrument Panel Compartment Lamp terminal 1
    • E37LR Dome/Reading Lamps - Left Rear terminal 1
    • E37RR Dome/Reading Lamps - Right Rear terminal 1
  10. Verify the test lamp turns ON and OFF when commanding the Inadvertent Load ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X7 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, disconnect the X7 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit terminal 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 
  11. Test or replace the courtesy lamp.
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