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Home >> Hummer >> 2008 >> H3 Base, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 172 (Lighting Systems) >> Diagnostic Information and Procedures >> Courtesy Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

Courtesy Lamps Malfunction - All

  1. Ignition OFF, disconnect the INT LAMP relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal R19 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the RIM.
  3. Verify that a test lamp illuminates between the B+ circuit terminal R17 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal R19 for a short to ground. If the circuit tests normal, test or replace the INT LAMP relay.
  4. Verify that a test lamp illuminates between the B+ circuit terminal R18 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the inoperative courtesy lamp.
  6. Ignition OFF, scan tool OFF, exterior lamps OFF, interior lamps OFF, test for less than 5.0 ohms between the inoperative courtesy lamp low control circuit terminal B and ground.
    • If greater than the specified range, test the low control circuit for an open/high resistance. If the circuit test normal, replace the RIM.
  7. Connect the harness connector at the inoperative courtesy lamp.
  8. Connect a 10A fused jumper wire between the B+ circuit terminal R17 and the control circuit terminal R19. Verify the courtesy lamps are ON.
    • If the courtesy lamps do not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the inoperative courtesy lamp.
  9. Connect a test lamp between the B+ circuit terminal R18 and the relay control circuit terminal R20.
  10. Command the courtesy lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the RIM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the RIM.
  11. If all circuits test normal, test or replace the INT LAMP relay.

Door Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate door courtesy lamp.
  2. Ignition OFF, scan tool OFF, interior lamps OFF, doors CLOSED, test for less than 1.0 ohm between the low control circuit terminal B and ground.
    • If greater than the specified range, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate door control module.
  3. Connect a test lamp between the high control circuit terminal A and the low control circuit terminal B.
  4. Command the exterior courtesy lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the high control circuit for a short to voltage. If the circuit tests normal, replace the appropriate door control module.
    • If the test lamp is always OFF, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate door control module.
  5. If all circuits test normal, test or replace the appropriate door courtesy lamp.

Courtesy Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the I/P dimmer switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the low reference circuit terminal 1.
    • If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the IPM.
  3. Ignition ON, verify the scan tool courtesy lamp switch parameter is OFF.
    • If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the IPM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool courtesy lamp switch parameter is ON.
    • 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 IPM.
  5. If all circuits test normal, test or replace the I/P dimmer switch.

Door Open Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative door latch assembly.
  2. Ignition OFF, interior lamps OFF, doors CLOSED, test for less than 5.0 ohms between the ground circuit and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool door open switch parameter is CLOSED.
    • If the not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the appropriate door control module.
  4. Install a 3A fused jumper wire between the signal circuit and ground. Verify the scan tool door open switch parameter is OPEN.
    • 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 appropriate door control module.
  5. If all circuits test normal, test or replace the inoperative door latch assembly.

Rear Compartment Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the rear compartment courtesy lamp.
  2. Ignition OFF, doors closed, interior lamps OFF, test for less than 5.0 ohms between the control circuit terminal C and ground.
    • If greater than the specified range, test the control circuit for an open/high resistance.
  3. Ignition OFF, connect a test lamp between the rear compartment lid ajar switch signal circuit terminal B and ground.
  4. Command the trunk release relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always OFF, test the rear compartment lid ajar switch signal circuit terminal B for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the rear compartment lid release actuator.
    • If the test lamp is always ON, test the rear compartment lid ajar switch signal circuit for a short to voltage. If the circuit tests normal, test or replace the rear compartment lid release actuator.
  5. If all circuits test normal, replace the rear compartment courtesy lamp.

Overhead Console Courtesy Lamp Malfunction - Front or Rear

  1. Ignition OFF, disconnect the harness connector at the inoperative overhead console lamp assembly.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 1.0 ohm between the low control circuit terminal B and ground.
    • If greater than the specified range, test the low control circuit for an open/high resistance. If the circuit test normal, replace the RIM.
  3. Ignition OFF, connect a test lamp between the courtesy lamp supply voltage circuit terminal A and the low control circuit terminal B.
  4. Command the courtesy lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always OFF, test the courtesy lamp supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RIM.
    • If the test lamp is always ON, test the courtesy lamp supply voltage circuit for a short to voltage. If the circuit tests normal, replace the RIM.
  5. If all circuits test normal, replace the inoperative overhead console lamp assembly.

I/P Compartment Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the I/P Compartment lamp switch.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 1.0 ohm between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition OFF, connect a test lamp between the courtesy lamp supply voltage circuit terminal B and the ground circuit terminal A.
  4. Command the courtesy lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always OFF, test the courtesy lamp supply voltage circuit for a short to ground or an open/high resistance.
    • If the test lamp is always ON, test the courtesy lamp supply voltage circuit for a short to voltage.
  5. If all circuits test normal, replace the I/P compartment lamp switch.

Reading Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative vanity mirror.
  2. Ignition OFF, scan tool OFF, interior lamps OFF, test for less than 1.0 ohm between the ground circuit terminal C and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the courtesy lamp voltage supply circuit terminal A and ground.
    • If the test lamp does not illuminate, test the courtesy lamp voltage supply circuit for a short to ground or an open/high resistance.
  4. If all circuits test normal, replace the inoperative reading lamp.

Vanity Mirror Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative vanity mirror.
  2. Ignition OFF, scan tool OFF, interior lamps OFF, test for less than 1.0 ohm between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, interior lamps ON, verify that a test lamp illuminates between the courtesy lamp voltage supply circuit terminal B and ground.
    • If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.
  4. If all circuits test normal, replace the inoperative vanity mirror.
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