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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 274 (Lighting System - DTC B3891 To DTC C0297 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Courtesy Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. 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.
  2. 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
    • E27 Instrument Panel Compartment Lamp terminal 2
    • E37LF Dome/Reading Lamps - Left Front terminal 6
    • E37RF Dome/Reading Lamps - Right Front terminal 6
    • E37LR Dome/Reading Lamps - Left Rear (Sedan) terminal B
    • E37RR Dome/Reading Lamps - Right Rear (Sedan) terminal B
    • E37R Dome/Reading Lamps - Rear (Coupe) 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.
    • If less than 10 Ω 
  3. 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
    • E27 Instrument Panel Compartment Lamp terminal 1
    • E37LF Dome/Reading Lamps - Left Front terminal 1
    • E37RF Dome/Reading Lamps - Right Front terminal 1
    • E37LR Dome/Reading Lamps - Left Rear (Sedan) terminal A
    • E37RR Dome/Reading Lamps - Right Rear (Sedan) terminal A
    • E37R Dome/Reading Lamps - Rear (Coupe) terminal 1
  4. 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.
      • 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.
    • If the test lamp turns ON and OFF 
  5. Test or replace the courtesy lamp.
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