GM Service Manual Online
For 1990-2009 cars only

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Action

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Schematic Reference: Interior Lights Schematics

1

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the headlamp switch in the HEADLAMP position.

Do the headlamps operate properly?

Go to Step 3

Go to Headlamps Inoperative - Low Beams

3

  1. Turn ON the ignition, with the engine OFF.
  2. Cover the ambient light sensor.
  3. Open and close both doors.
  4. Unlock both doors with the key.
  5. Place the interior lamp switch in the ON position.

Do the courtesy lamps operate properly?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 4

4

Are the courtesy lamps inoperative only with the interior lamps switch?

Go to Step 8

Go to Step 5

5

Are the courtesy lamps only inoperative when a door is opened?

Go to Step 10

Go to Step 6

6

Are the courtesy lamps only inoperative when a door is unlocked?

Go to Step 13

Go to Step 7

7

Is there only one inoperative lamp?

Go to Step 16

Go to Step 18

8

  1. Place the interior lamp switch in the ON position.
  2. With a scan tool, observe the Interior Lamp Switch parameter in the instrument cluster (IPC) data list.

Does the scan tool display ON?

Go to Step 40

Go to Step 9

9

  1. Disconnect the headlamp switch.
  2. Connect a 3 amp fused jumper between the interior lamp switch signal circuit and a good ground.
  3. With a scan tool, observe the Interior Lamp Switch parameter in the instrument cluster (IPC) data list.

Does the scan tool display ON?

Go to Step 38

Go to Step 28

10

  1. Open both doors.
  2. With a scan tool, observe both of the Door Jamb Switch parameters in the Body Control Module (BCM) inputs data list.

Does the scan tool indicate that both of the Door Jamb Switch parameters are on?

Go to Step 39

Go to Step  11

11

  1. Turn OFF the ignition.
  2. Disconnect the appropriate door lock actuator.
  3. Connect a 3 amp fused jumper between the door open switch signal circuit and a good ground.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the Door Jamb Switch parameter.

Does the scan tool indicate that the Door Jamb Switch parameter is on?

Go to Step 12

Go to Step 29

12

  1. Connect a 3 amp fused jumper between the door open switch signal circuit and the door lock actuator ground circuit.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Door Jamb Switch parameter.

Does the scan tool indicate that the Door Jamb Switch parameter is on?

Go to Step 36

Go to Step 43

13

  1. Unlock the driver door with the key.
  2. With a scan tool, observe the Key Cylinder Unlock Switch parameter in the Body Control Module (BCM) input data list.
  3. Unlock the passenger door with the key.
  4. With a scan tool, observe the Key Cylinder Unlock Switch parameter.

Did the scan tool display ON when each door lock cylinder switch was turned to the UNLOCK position?

Go to Step 39

Go to Step 14

14

  1. Disconnect the appropriate door lock cylinder switch.
  2. Connect a 3 amp fused jumper between the door key switch signal circuit and a good ground.
  3. With a scan tool, observe the Key Cylinder Unlock Switch parameter.

Does the scan tool indicate that the Key Cylinder Unlock Switch parameter is on?

Go to Step 15

Go to Step 30

15

  1. Connect a 3 amp fused jumper between the door key switch signal circuit and the ground circuit of the door lock cylinder switch.
  2. With a scan tool, observe the Key Cylinder Unlock Switch parameter.

Does the scan tool indicate that the Key Cylinder Unlock Switch parameter is on?

Go to Step 37

Go to Step 42

16

  1. Remove the inoperative courtesy lamp bulb(s).
  2. Connect a test lamp between the supply voltage circuit of the inoperative courtesy lamp and a good ground.

Does the test lamp illuminate?

Go to Step 17

Go to Step 46

17

Connect a test lamp between the supply voltage circuit of the inoperative courtesy lamp and the ground circuit of the inoperative courtesy lamp.

Does the test lamp illuminate?

Go to Step 41

Go to Step 45

18

With a scan tool, command the Inadvertent Power relay ON and OFF.

Do you hear a click when you command the relay ON and OFF?

Go to Step 21

Go to Step 19

19

  1. Turn OFF the ignition.
  2. Disconnect the Inadvertent Power relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the Inadvertent Power relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 20

Go to Step 48

20

  1. Connect a test lamp between the battery positive voltage circuit of the Inadvertent Power relay coil and the control circuit of the Inadvertent Power relay.
  2. With a scan tool, command the Inadvertent Power relay on.

Does the test lamp illuminate?

Go to Step 34

Go to Step 31

21

  1. Turn OFF the ignition.
  2. Disconnect the Inadvertent Power relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the Inadvertent Power relay switch and a good ground.

Does the test lamp illuminate?

Go to Step 22

Go to Step 49

22

Connect a 50 amp fused jumper between the battery positive voltage circuit of the Inadvertent Power relay switch and the interior lamp fuse supply voltage circuit.

Do the courtesy lamps operate properly?

Go to Step 34

Go to Step 23

23

With a scan tool, command the COURTESY relay ON and OFF.

Do you hear a click when you command the COURTESY relay ON and OFF?

Go to Step 26

Go to Step 24

24

  1. Turn OFF the ignition.
  2. Disconnect the COURTESY relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the COURTESY relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 25

Go to Step 33

25

  1. Connect a test lamp between the battery positive voltage circuit of the COURTESY relay coil and the control circuit of the COURTESY relay.
  2. With a scan tool, command the COURTESY relay ON.

Does the test lamp illuminate?

Go to Step 35

Go to Step 32

26

  1. Turn OFF the ignition.
  2. Disconnect the COURTESY relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the COURTESY relay coil and the ground circuit of the COURTESY relay switch.

Does the test lamp illuminate?

Go to Step 27

Go to Step 44

27

Connect a 10 amp fused jumper between the ground circuit of the COURTESY relay switch and the interior lamp control circuit.

Do the interior lamps illuminate?

Go to Step 35

Go to Step 50

28

Test the interior lamp switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 40

29

Test the door open switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 39

30

Test the door key switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 39

31

Test for an open or high resistance in the control circuit of the Inadvertent Power relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 39

32

Test for an open or high resistance in the control circuit of the COURTESY relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 39

33

Test for an open or high resistance in the interior lamp fuse supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

Go to Step 47

34

Inspect for poor connections at the Inadvertent Power relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 52

35

Inspect for poor connections at the COURTESY relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 53

36

Inspect for poor connections at the harness connector of the door lock actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 51

37

Inspect for poor connections at the harness connector of the door lock cylinder switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 54

38

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 55

39

Inspect for poor connections at the harness connector of the Body Control Module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 56

40

Inspect for poor connections at the harness connector of the Instrument Cluster (IPC). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 57

41

Inspect for poor connections at the inoperative courtesy lamp bulb connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 59

Go to Step 58

42

Repair an open or high resistance in the door lock cylinder switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

43

Repair an open or high resistance in the door lock actuator ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

44

Repair an open or high resistance in the ground circuit of the COURTESY relay switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

45

Repair the high resistance or open in the ground circuit of the inoperative courtesy lamp. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

46

Repair the high resistance or open in the supply voltage circuit of the courtesy lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

47

Repair the high resistance or open in the battery positive voltage circuit of the COURTESY relay coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

48

Repair the high resistance or open in the battery positive voltage circuit of the Inadvertent Power relay coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

49

Repair the high resistance or open in the battery positive voltage circuit of the Inadvertent Power relay switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

50

Repair the open or high resistance in the interior lamp control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 59

--

51

Replace the door lock actuator. Refer to Door Lock Actuator Replacement in Doors.

Did you complete the replacement?

Go to Step 59

--

52

Replace the Inadvertent Power relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 59

--

53

Replace the COURTESY relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 59

--

54

Replace the door lock cylinder switch. Refer to Door Lock Cylinder Replacement in Doors.

Did you complete the replacement?

Go to Step 59

--

55

Replace the headlamp switch. Refer to Headlamp Switch Replacement

Did you complete the replacement?

Go to Step 59

--

56

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 59

--

57

Replace the Instrument Cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

Go to Step 59

--

58

Replace the inoperative courtesy lamp bulb.

Did you complete the replacement?

Go to Step 59

--

59

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2