GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Important: The sunload sensor assembly must indicate low light conditions for the interior lamps to operate.

  1. Cover the sunload sensor assembly.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the courtesy lamps.
  4. Open and close all of the doors.
  5. Turn the interior lamp switch ON and OFF.
  6. Turn OFF the ignition.

Do the courtesy lamps operate properly?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the Ambient Light Status parameter in the HVAC lighting data list.
  4. Cover the sunload sensor assembly.

Does the scan tool display DARK?

Go to Step 4

Go to Twilight Sentinel Inoperative

4

With a scan tool, command the Courtesy Lamps ON from the rear integration module (RIM) lighting output controls data list.

Do all of the interior courtesy lamps turn ON?

Go to Step 6

Go to Step 5

5

Are all interior courtesy lamps inoperative?

Go to Step 10

Go to Step 14

6

  1. Turn the interior lamp switch ON.
  2. With a scan tool, observe the Courtesy Lamp Switch parameter in the instrument panel module (IPM) inputs data list.

Does the scan tool display ON?

Go to Step 7

Go to Step 8

7

  1. Open all the doors.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe all Door Open Switch parameters in the individual door module data lists.

Does the scan tool display OPEN for all Door Open Switch inputs?

Go to Step 28

Go to Step 9

8

  1. Disconnect the instrument panel (I/P) dimmer switch.
  2. Connect a 3-amp fused jumper between the courtesy lamp switch ON signal circuit and the I/P dimmer switch low reference circuit at the I/P dimmer switch harness connector.
  3. With a scan tool, observe the Courtesy Lamp Switch parameter.

Does the scan tool display ON?

Go to Step 25

Go to Step 15

9

  1. Turn OFF the ignition.
  2. Disconnect the inoperative door latch assembly.
  3. Connect a 3-amp fused jumper between the door open switch signal circuit of the inoperative door latch and the ground circuit of the door latch assembly.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, observe the inoperative Door Open Switch input parameter.

Does the scan tool display OPEN for the inoperative Door Open Switch input?

Go to Step 23

Go to Step 17

10

  1. Turn OFF the ignition.
  2. Disconnect the interior lamp relay located in the right rear fuse block.
  3. Turn ON the ignition, with the engine OFF.
  4. Turn the interior lamp switch ON.
  5. Probe the interior lamp relay control side supply voltage circuit with a test lamp connected to ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 30

11

Probe the interior lamp relay switch side supply voltage circuit with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 29

12

Connect a test lamp between the interior lamp relay control side supply voltage circuit and the courtesy lamp relay control circuit.

Does the test lamp Illuminate?

Go to Step 13

Go to Step 21

13

Connect a test lamp between the switch side supply voltage circuit of the interior lamp relay and the courtesy lamp supply control circuit of the interior lamp relay.

Do the test lamp illuminate?

Go to Step 22

Go to Step 19

14

  1. Turn ON the courtesy lamps.
  2. Remove the inoperative courtesy lamp bulb.
  3. Connect a test lamp between the inoperative courtesy lamp supply voltage circuit and the ground circuit of the inoperative courtesy lamp.

Does the test lamp illuminate?

Go to Step 28

Go to Step 19

15

Test the courtesy lamp switch ON signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 16

16

Test the I/P dimmer switch low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 26

17

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

Did you find and correct the condition?

Go to Step 38

Go to Step 18

18

Test the inoperative door latch assembly ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 24

19

Test the courtesy lamp supply voltage circuit for an open, high resistance, or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 20

20

Test the courtesy lamp supply control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 27

21

Test the courtesy lamp relay control circuit for an open, high resistance, or a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 27

22

Inspect for poor connections at the interior lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 31

23

Inspect for poor connections at the harness connector of the inoperative door latch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 32

24

Inspect for poor connections at the harness connector of the inoperative door control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 33

25

Inspect for poor connections at the harness connector of the I/P dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 34

26

Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 35

27

Inspect for poor connections at the harness connector of the RIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 38

Go to Step 36

28

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

Did you find and correct the condition?

Go to Step 38

Go to Step 37

29

Locate and repair an open, high resistance, or short to ground in the switch side supply voltage circuit of the interior lamp relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 38

--

30

Locate and repair an open, high resistance, or short to ground in the control side supply voltage circuit of the interior lamp relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 38

--

31

Replace the in interior lamp relay. Refer to Wiring Repairs .

Did you complete the replacement?

Go to Step 38

--

32

Replace the inoperative door latch assembly. Refer to Front Side Door Lock Replacement or Rear Door Lock Replacement .

Did you complete the replacement?

Go to Step 38

--

33

Replace the inoperative door control module. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 38

--

34

Replace I/P dimmer switch. Refer to Instrument Panel Lamp Dimmer Switch Replacement .

Did you complete the replacement?

Go to Step 38

--

35

Replace the IPM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 38

--

36

Replace the RIM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 38

--

37

Replace the inoperative courtesy lamp bulb. Refer to Instrument Panel Courtesy Lamp Bulb Replacement - Right Side and Overhead Console Courtesy Lamp Replacement .

Did you complete the replacement?

Go to Step 38

--

38

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2