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Home >> Chevrolet >> 2019 >> Suburban 3500 HD LS >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System - Diagnostic Information And Procedures (DTC B3950-C0297) >> Diagnostic Information and Procedures >> Dome Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

Dome Lamp Switch Malfunction

  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, open and close drivers door, disconnect the harness connector at the S12 Dome Lamp Switch. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 15 Ω between the ground circuit terminal 1 and ground.
    • If 15 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 15 Ω 
  3. Ignition ON.
  4. Verify the scan tool Interior/Courtesy Lighting Master Switch parameter is Door.
    • If Cancel 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit terminal 2 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 On 
    1. Ignition OFF, disconnect the X7 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the signal circuit terminal 3 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 Door 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground.
  6. Verify the scan tool Interior/Courtesy Lighting Master Switch parameter is Cancel.
    • If not Cancel 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit terminal 2 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 Cancel 
  7. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground.
  8. Verify the scan tool Interior/Courtesy Lighting Master Switch parameter is On.
    • If not 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 signal circuit terminal 3 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 On 
  9. Test or replace the S12 Dome Lamp Switch.

Dome/Courtesy Lamps Malfunction

    NOTE:

    Each component with backlighting may need to be disconnected to isolate a short to voltage or short to ground. Use the wiring schematics to identify the following:

    • Backlighting components the vehicle is equipped with
    • Each component's control and ground circuit terminals
    • Component locations on the backlighting control circuit
  1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, open and close drivers door, disconnect the harness connector at the component with the inoperative dome/courtesy lamp. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 15 Ω between the appropriate ground circuit terminal listed below and ground.
    • E36AH Dome Lamp terminal B (Z75 without SWB)
    • E37B Dome/Reading Lamps - 2nd Row terminal B (without U42)
    • E37C Dome/Reading Lamps - 3rd Row terminal B (without DNU)
    • E37H Dome/Reading Lamps - Left Roof Rail terminal 4 (with AZ3)
    • E37J Dome/Reading Lamps - Right Roof Rail terminal 4 (with AZ3)
    • E37EL Dome/Reading Lamps - Front Overhead Console Left terminal 4
    • E37ER Dome/Reading Lamps - Front Overhead Console Right terminal 4
    • E8A Door Sill Plate Lamp - Driver terminal 2 (with Z75)
    • E8B Door Sill Plate Lamp - Passenger terminal 2 (with Z75)
    • E8Q Door Sill Plate Lamp - Left Rear terminal 2 (with Z75)
    • E8R Door Sill Plate Lamp - Right Rear terminal 2 (with Z75)
    • P22A Video Display - 2nd Row terminal 2 (with U42)
    • P22B Video Display - 3rd Row terminal 2 (with DNU)
    • If 15 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 15 Ω 
  3. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
    • E36AH Dome Lamp terminal A (Z75 without SWB)
    • E37B Dome/Reading Lamps - 2nd Row terminal C (without U42)
    • E37C Dome/Reading Lamps - 3rd Row terminal C (without DNU)
    • E37H Dome/Reading Lamps - Left Roof Rail terminal 3 (with AZ3)
    • E37J Dome/Reading Lamps - Right Roof Rail terminal 3 (with AZ3)
    • E37EL Dome/Reading Lamps - Front Overhead Console Left terminal 3
    • E37ER Dome/Reading Lamps - Front Overhead Console Right terminal 3
    • E8A Door Sill Plate Lamp - Driver terminal 1 (with Z75)
    • E8B Door Sill Plate Lamp - Passenger terminal 1 (with Z75)
    • E8Q Door Sill Plate Lamp - Left Rear terminal 1 (with Z75)
    • E8R Door Sill Plate Lamp - Right Rear terminal 1 (with Z75)
    • P22A Video Display - 2nd Row terminal 3 (with U42)
    • P22B Video Display - 3rd Row terminal 3 (with DNU)
  4. Verify the test lamp turns ON and OFF when commanding the Courtesy Lamps 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 
  5. Test or replace the dome/courtesy lamp.
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