GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition to the ON position.
  2. Turn the headlamp switch to the PARK position.
  3. Turn the instrument panel (I/P) lamp dimmer switch to a high position.

Are all the I/P lamps ON?

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

Go to Step 3

3

Are all of the instrument panel lamps inoperative?

Go to Step 11

Go to Step 4

4

Are any of the steering wheel control lamps inoperative?

Go to Step 5

Go to Step 14

5

Is one steering wheel control switch illuminated?

Go to Step 7

Go to Step 6

6

  1. Remove both steering wheel control switches.
  2. Probe the I/P lamp supply circuit of each switch with a test lamp connected to ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate a each supply circuit?

Go to Step 9

Go to Step 8

7

  1. Remove the inoperative switch.
  2. Probe the I/P lamp dimming supply circuit of the inoperative switch with a test lamp connected to ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

Go to Step 9

Go to Step 8

8

Test for a high resistance, short to ground or an open in the I/P dimming lamp supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 15

9

Test for a high resistance or an open in the I/P dimming lamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 15

10

  1. Disconnect the headlamp switch.
  2. Install a fused jumper between the dimming potentiometer reference voltage circuit and the I/P lamps dimming control circuit.

Do the instrument panel lamps turn on?

Go to Step 18

Go to Step 19

11

Inspect the instrument panel lamps dimming control circuit for a short to ground, short to battery positive voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 12

12

Inspect the dimming potentiometer reference voltage circuit for high resistance, short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 13

13

Test for a short to ground in the instrument panel lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 10

14

Inspect for a high resistance or an open in the inoperative I/P lamp component supply voltage circuit or the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 17

15

Inspect for a poor connection at the harness connector of the steering wheel control switches. 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 20

Go to Step 16

16

Replace the inoperative switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column.

Did you complete the repair?

Go to Step 20

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17

Replace the inoperative component or bulb.

Did you complete the repair?

Go to Step 20

--

18

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 20

--

19

Replace the body control module (BCM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3