GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Dome/Reading Lamp Control

B2615 00

B2615 00

B2615 00

--

Dome/Reading Lamp Supply Voltage

1

1

--

--

Dome Lamp Switch Signal

2

2

2

--

Exterior Lamps Illumination Supply Voltage

3

3

3

--

I/P Dimmer Switch Ground

--

2

--

--

LH Vanity Mirror Courtesy Lamp Ground

--

4

--

--

Overhead Console Courtesy/Reading Lamp Ground

--

4

--

--

Rear Dome Lamp Ground

--

1

--

--

RH Vanity Mirror Courtesy Lamp Ground

--

4

--

--

  1. Courtesy Lamps Malfunction
  2. Dome Lamp Switch Malfunction
  3. Exterior Lamps Malfunction
  4. Reading/Vanity Mirror Lamps Malfunction

Circuit/System Description

The courtesy lamps include the reading lamps, cargo lamp, and dome lamps. The cargo lamp and dome lamps may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. When the driver places the dome lamp defeat switch in the OFF position, these courtesy lamps will be disabled. If a door is opened, the courtesy lamps illuminate. After all the doors have been closed, the courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. The courtesy lamps will also turn ON prior to any door being opened and will remain illuminated approximately 40 seconds when the driver removes the ignition key. The body control module (BCM) will immediately turn OFF the courtesy lamps if a door lock command is received with all of the doors closed, or if the ignition switch is turned to either the ON or RUN position.

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 for scan tool information

Circuit/System Verification

  1. Verify that the courtesy lamp switch parameter displays Active and Inactive while operating the courtesy lamp switch ON and OFF.
  2. If the scan tool parameter does not display the correct state in relation to the actual switch position, refer to the Courtesy Lamp Switch Malfunction.
  3. Verify that the interior lamp defeat switch parameter displays ON and OFF while operating the interior lamp defeat switch ON and OFF.
  4. If the scan tool parameter does not display the correct state in relation to the actual switch position, refer to the Courtesy Lamp Switch Malfunction.
  5. Verify that the courtesy lamps turn ON and OFF while operating any door Opened and Closed.
  6. If all interior lamps do not illuminate, refer to Door Ajar Indicator Malfunction
  7. Turn the front and rear reading lamps ON and OFF. The lamps should turn ON and OFF when activated.
  8. If the reading lamps do not turn ON and OFF, refer to Reading Lamps Malfunction.
  9. Verify the vanity mirror lamps turn ON and OFF as the vanity mirror is Opened and Closed.
  10. If the vanity mirrors do not turn ON and OFF, refer to Vanity Mirror Malfunction.
  11. If the switch circuits test normal, refer to the Courtesy Lamp Malfunction.

Circuit/System Testing

Courtesy Lamp Switch Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the headlamp switch.
  2. Test for less than 5.0 ohms between the ground circuit terminal C and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Courtesy Lamp Switch parameter is Inactive.
  5. If not the specified value, test the signal circuit termina  J for a short to ground. If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal J and the ground circuit terminal C. Verify the scan tool Courtesy Lamp Switch parameter is Active.
  7. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  8. Ignition ON, verify the scan tool Interior Lamp Defeat Switch parameter is OFF.
  9. If not the specified value, test the signal circuit terminal M for a short to ground. If the circuit tests normal, replace the BCM.
  10. Install a 3A fused jumper wire between the signal circuit terminal M and the ground circuit terminal C. Verify the scan tool Interior Lamp Defeat Switch parameter is ON.
  11. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  12. If all circuits test normal, test or replace the headlamp switch.

Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative courtesy lamp.
  2. Test for less than 5.0 ohms between the ground circuit terminal B 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 A and the ground circuit terminal B.
  5. Turn the courtesy lamp switch ON and OFF. 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 BCM.
    If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the inoperative courtesy lamp.

Reading Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative courtesy/reading lamp center.
  2. Test for less than 5.0 ohms between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the inadvertent power supply circuit terminal C and ground.
  5. If the test lamp does not illuminate, test the inadvertent power supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Connect the harness connector at the courtesy/reading lamp center, and remove the reading lamp bulb.
  7. Connect a test lamp across the bulb terminals.
  8. Turn the reading lamp switch ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states.
  9. If the test lamp is always ON, replace the inoperative courtesy/reading lamp center.
    If the test lamp is always OFF, replace the inoperative courtesy/reading lamp center.
  10. If all circuits test normal, test or replace the inoperative reading lamp bulb.

Vanity Mirrors Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative vanity mirror lamp.
  2. Test for less than 5.0 ohms between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the inadvertent power supply circuit terminal A and ground.
  5. If the test lamp does not illuminate, test the inadvertent power supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Connect the harness connector at the vanity mirror lamp, and remove the vanity lamp bulb.
  7. Connect a test lamp across the bulb terminals.
  8. Open and close the vanity mirror. The test lamp should turn ON and OFF when changing between the commanded states.
  9. If the test lamp is always ON or OFF, replace the inoperative vanity mirror lamp.
  10. If all circuits test normal, test or replace the inoperative vanity lamp bulb.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Dome and Reading Lamp Bulb Replacement
    •  Headlamp Switch Replacement
    •  Sunshade Illuminated Mirror Lamp Bulb Replacement
    •  Control Module References for BCM or door module replacement, setup, and programming