GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle
    • Review Strategy Based Diagnosis
    •  Diagnostic Procedure Instructions

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Dome/Courtesy Lamp Control

B2615 02

2

1

--

Dome/Courtesy Lamp Control

2

2

1

--

Courtesy Lamp Control

--

2

--

--

1.Dome/Courtesy lamps always illuminated

2. Dome/Courtesy lamps do not illuminate

Circuit/System Description

Battery voltage for the courtesy lamps is supplied at all times to the body control module (BCM). When the BCM receives a signal to command the courtesy lamps ON, it then applies voltage through the dome/courtesy lamps control circuit to the courtesy lamps listed below.

    • Accent lamp - left lower I/P
    • Accent lamp - right lower I/P
    • Accent lamp - driver seat
    • Accent lamp - passenger seat
    • Accent lamp - driver door handle
    • Accent lamp - passenger door handle
    • Compartment courtesy lamp

Reference Information

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References

Circuit/System Verification

  1. Observe the driver information center while opening and closing each vehicle door and the liftgate. The driver information center should display the door ajar/liftgate ajar message only when the door/liftgate is open.
  2. If the driver information center displays the door ajar/liftgate ajar message when a door or the liftgate is closed, refer to Door Ajar Indicator Malfunction
    If the door ajar/liftgate is functioning normal, refer to Courtesy Lamp Circuit Malfunction.

Circuit/System Testing

Courtesy Lamp Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate inoperative courtesy lamp.
  2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 2.
  5. Command the Courtesy Lamps test ON and OFF with the scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  6. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).
    If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).
  7. If all circuits test normal, test or replace the appropriate inoperative courtesy lamp.

Repair Instructions

Perform the Diagnostic Repair Verification

    •  Front Side Door Sill Courtesy Lamp Replacement
    •  Rear Compartment Courtesy Lamp Replacement
    •  Control Module References