GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics

1

Did you perform the Lighting Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the parklamps.
  2. Ensure the panel dimmer switch is at maximum illumination.

Do the illumination lamps operate normally?

Go to Testing for Electrical Intermittents in Wiring Systems

Go to Step 3

3

Is only one lamp inoperative?

Go to Step 4

Go to Step 6

4

Test the instrument panel lamp supply voltage circuit of the inoperative lamp for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 5

5

Test the ground circuit of the inoperative lamp for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 11

6

Do the park lamps function properly?

Go to Step 7

Go to Park Lamps Inoperative

7

Inspect the ILLUM fuse.

Is the fuse open?

Go to Step 12

Go to Step 8

8

  1. Ensure the panel dimmer switch is at maximum illumination.
  2. Connect a test lamp between the ILLUM fuse and ground.

Does the test lamp illuminate?

Go to Step 14

Go to Step 9

9

without disconnecting the switch, connect a test lamp between the instrument panel lamps dimmer switch signal circuit at the headlamp and panel dimmer switch and ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 10

10

Inspect for poor connections at the harness connector of the headlamp and panel dimmer 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 17

Go to Step 16

11

Inspect for poor connections at the harness connector of the inoperative bulb. 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 17

Go to Step 15

12

  1. Repair the short to ground in the instrument panel lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.
  2. Replace the fuse.

Did you complete the repair?

Go to Step 17

--

13

Repair the open in the instrument panel lamps dimmer switch signal circuit between the switch and the fuse. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

14

Repair the open in the instrument panel lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

15

Replace the inoperative bulb.

Did you complete the replacement?

Go to Step 17

--

16

Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3